Medical Oncology & Hematology
Dr Steven Gruenstein is an Associate Clinical Professor of Medicine, in Hematology and Medical Oncology, at the Mount Sinai School of Medicine. He is an Attending Physician both at Mount Sinai and Lenox Hill.
Dr Gruenstein completed his sub specialty training at Beth Israel Hospital after which he became board certified in Medical Oncology, Hematology and earlier in Internal Medicine. He is a member of the American Society of Clinical Oncology, the American Society of Hematology, American Society of Breast Diseases among others.
Dr Gruenstein is recognized throughout the NY Metropolitan as an outstanding clinical Hematologist/Oncologist dedicated to his patients’ wellbeing. He is their advocate. He is also known for kindness and compassion which is evident immediately upon meeting him. He has been honored with citations in New York Magazine’s Best Doctor’s, Castle Connelly’s Best Doctors in US and NY, Patients’ Choice and Compassionate Doctor’s Awards. He has been described, interviewed and quoted in books, magazines and newspapers. He has published extensively in his field.
Dr. Gruenstein is especially interested in hematological malignancies, benign hematology and solid tumors especially gastrointestinal, genitourinary and breast cancer. He treats other cancers as well, and is an expert in benign hematology. He teaches at both Mount Sinai and Lenox Hill, lecturing on many topics, directing tumor boards and serving on various hospital administrative boards. For patients seeking more time and personalized attention, Dr Gruenstein offers a special Concierge Service.
| Lenox Hill Hospital |
| Mount Sinai Manhattan |
Patient Reviews
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"Dr. Gruenstein is phenomenal.
I have never met a Doctor Who has been in the top of his field, and also made it easy for a patient to understand their situation. From his smile to his kindness to his easy explanations. I feel honored to be one of his patients. He is certainly not for 15 minutes revolving door type of doctor. They don’t unfortunately make doctors like him anymore."
from 43Loretta 5.0 Stars - (2025-02-13) -
"I am incredibly grateful to be under the care of Dr. Gruenstein. From my very first visit, he has been nothing but super caring, professional, and knowledgeable, always taking the time to listen and answer all my questions with patience and clarity. His compassionate approach truly makes a difference in this journey.
Beyond his expertise, Dr. Gruenstein has built an amazing team—everyone in his office is kind, supportive, and highly efficient. The level of coordination and attention to detail they provide makes every appointment seamless and reassuring.
If you’re looking for a doctor who genuinely cares about his patients and provides top-notch medical care, I highly recommend Dr. Gruenstein. I couldn’t ask for a better team to guide me through treatment!"
from Anna 5.0 Stars - (2025-02-12) -
"Couldn’t be more grateful for Dr. Gruenstein’s care. He is fabulous and has guided my cancer care for over two years; he is knowledgeable and a strong communicator."
from Marian 5.0 Stars - (2025-02-08) -
"Friendly staff at checkin and checkout. Excellent phlebotomists - the experience is painless and quick, and they are kind and cheerful. Nurse Practitioner Alexandria is absolutely one of best health care providers I have been fortunate enough to have on my ‘care team’. She is extremely knowledgeable, takes time to answer all questions, and is compassionate and caring."
from Ann 5.0 Stars - (2025-02-01) -
"Thank you so much for taking such great care of me! Dr. Gruenstein is the very best MD I have ever come across. Both he and his staff were very caring, attentive and considerate. i highly recommend him and his office ."
from Mira 5.0 Stars - (2025-02-01) -
"My entire experience for the first time visiting Dr. Gruenstein’s office was exceptional. From the front desk personnel, to the nurse practitioner, to the phelpotomist, to Dr. Gruenstein conducting his examination, I was treated in a very caring manner. Everyone was very thorough. and took the time and listened to what I had to say. Dr. Gruenstein made me feel confident that I was in good hands."
from Thomas 5.0 Stars - (2025-01-23) -
"Dr Steven Gruenstein has a warm, approachable bedside manner and listens to all your concerns. He is meticulous and comprehensive in his search for causation of illness. I always look forward to my visits with Dr Gruenstein."
from man 5.0 Stars - (2025-01-09) -
"The greatest service staff
The fantastic caring doctor"
from Sharon 5.0 Stars - (2025-01-03) -
"Excellent customer service, clean, not a long wait time. Very comforting"
from Philip 5.0 Stars - (2025-01-01) -
"Hands down the scammiest doctor I have ever encountered. Not only was he creepy and inappropriate during my in-person visit, but he insisted on doing a full hematology panel (far beyond what I had been referred for or had been expecting), which as I had feared, resulted in a huge surprise medical bill.
To interpret my results (which were very simple), Gruenstein's office insisted I set up an in-person visit, which was unnecessary. I asked for a remote visit, and when they finally allowed that, no one contacted me at the scheduled time. His nurse finally called me, 45 minutes late, and "explained" my results, which I had already received online, for 30 seconds. I was billed $300 for this "visit".
I will never go back to this office - total scam and was a very uncomfortable experience."
from Audrey 1.0 Stars - (2024-12-30)