Spontaneous pneumothorax (SP) caused by necrosis in combination with regression of lung metastases is a rare complication to cancer chemotherapy. Few case reports have previously been presented, and mostly in patients with sarcomas. A patient is presented with spontaneous pneumothorax probably caused by chemotherapy-induced cell necrosis in bilateral lung metastases secondary to an endometrioid cancer. The literature is surveyed. Because of the increasing use of effective chemotherapeutic drugs, it is expected that this rare complication will occur more often.