Background/Purpose: This study determined general characteristics of cancer patients who developed medication related osteonecrosis of the jaw (MRONJ). Materials and methods: Demographic and clinical data of 35 cancer patients with MRONJ were retrospectively evaluated. General characteristics were compared between cases with and without complete recovery, to determine factors related to complete treatment response. Results: Seventeen female and 18 male patients (45-82 years) were included. Primary diagnoses were breast cancer (34.3%), prostate cancer (31.4%), or multiple myeloma (14.3%). Most patients (82.9%) used only intravenous zoledronic acid. Median bisphosphonate treatment duration was 36 months (5-120 months) and median time from commencing to stopping medication due to MRONJ progression was 6.5 months (1-84 months). Nearly all patients had a history of surgical procedures (88.6%), or trauma from dentures (5.7%). Half of the patients were treated conservatively (51.4%), and one-third were treated surgically (31.4%). Less than half of the patients recovered completely after treatment (42.9%), and 48.6% improved partially. Conclusion: MRONJ develops with prolonged use of bisphosphonates, but can develop after as little as 5 months of intravenous bisphosphonate treatment. Oncologists and dentists should be aware of this clinical aspect and ensure early determination of lesions when they are still curable.