Gemcitabine is a chemotherapeutic agent with proven antitumor effects in pancreatic and non-small cell lung cancer; however, studies establishing the definite significance in other solid tumors are still in progress. We herein present three female patients with advanced breast cancer who received gemcitabine as salvage chemotherapy. Gemcitabine at a dose of 1250 mg/m2 was scheduled for days 1, 8 and 15 with a subsequent rest for 1 week. However, within 1 week after the very first administration of gemcitabine myelotoxicity WHO grade IV occurred in all patients, leading to discontinuation of therapy. In two patients this gemcitabine-induced hematotoxicity could be overcome by means of vigorous supportive care, but one patient died after cerebral bleeding due to severe thrombocytopenia. We conclude that gemcitabine in heavily pretreated breast cancer patients should only be used with extreme caution with special focus on platelet counts until solid data from clinical studies for doses and schedules are available.