Introduction: Steroids are a useful component of combination chemotherapy or as a single agent in the treatment of haematological disorders even though there are adverse effects associated with its use. Methods: We report four patients who developed diabetes mellitus (DM) during treatment with steroids for haematological disorders despite a negative history of DM. Results: The mean age of the patients was 55yrs and DM was diagnosed by fasting plasma glucose (FPG) after a cumulative steroid dose of 500-1800mg. Conclusion: It is necessary to have a baseline and frequent FPG in patients who are considered for combination chemotherapy which include steroid since the development of DM does not appear to be dose dependent or related to history of DM in the patient or family.