All Phase II studies with diglycoaldehyde with leukemia and solid tumors have been reviewed. The dose schedules employed ranged from 1.5 to 2.0 g/m2/day for 3 to 5 days. The most common side effects have been gastrointestinal (nausea and vomiting), which occurred in 22% of the patients. Renal toxicity (rise in BUN, creatinine, and urinary proteins) was seem in 17% of the patients treated. Other infrequent toxicities include hypocalcemia (9%) and local complications such as phlebitis. Leukopenia, thrombocytopenia, positive Coombs' test and impairment in coagulation profile were also reported. In contrast to the hints of therapeutic efficacy described during Phase I trials, in phase II trials no activity was noted among 96 patients with solid tumors and only minimal antileukemic action among 49 other patients. These disappointing Phase II trials coupled with prominent toxicities have prompted the decision to terminate further clinical testing. This report summarizes all clinical observations as an example of circumstances which curtail clinical testing of anticancer drugs.