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Languages: English, Italian

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.

Credentials:  MD
Education & Training
   FACP:    Beth Israel Medical Center
   Residency:    Metropolitan Hospital Center
   Medical School:    University of Genoa
   College:    Yeshiva University


Patient Reviews

  • "Dr. Gruenstein is the best! Very funny, cultured, and knows his stuff! He's also a very empathetic and lovely human. Excellent doctor and team."
      from Serena 5.0 Stars - (2025-09-02)
  • "I had my first appointment with Dr Gruenstein today. His bedside manner was the best I’ve seen so far, you can tell him and his staff truly care about their patients well being. I loved the thoroughness with his and his teams questioning. Grateful to have found him and look forward to having him as my doctor going forward. Have fun in Italy Dr G!"
      from Gianni 5.0 Stars - (2025-08-29)
  • "The staff, nurse practioner and doctor were very professional, informative and helpful. This was a very good experience and I highly recommend Dr. Gruenstein"
      from maureen 5.0 Stars - (2025-08-22)
  • "First visit was a good experience. Appointment began right on time and the nurse practitioners were courteous and professional as well as the receptionists who greeted me upon arrival at the office. The physician’s assistant was very courteous and conducted her examination in a very professional manner. Dr. Gruenstein had a very pleasant bedside manner and was very reassuring."
      from Brian 5.0 Stars - (2025-08-20)
  • "Excellent experience."
      from Karen 5.0 Stars - (2025-08-20)
  • "BEST Hematologist EVER!!! Him & his staff are so kind and professional. I didn’t wait long to be seen, maybe 3min? He makes you feel safe & like everything is going to be ok."
      from 5.0 Stars - (2025-08-19)
  • "Great, compassionate care."
      from Darrell 5.0 Stars - (2025-08-16)
  • "professional, well run office. Excellent Medical care and knowledge."
      from jill 5.0 Stars - (2025-08-05)
  • "The whole staff was wonderful 🥰🌹🙏🏼"
      from Joyce 5.0 Stars - (2025-08-05)
  • "My first visit with the doctor very pleasant also informative made me feel comfortable very hopeful of success in my upcoming treatment I also spoke to the Nurse Practitioner very helpful looking forward to her assistance overall the staff were extremely helpful"
      from Rosalinda 5.0 Stars - (2025-08-05)