A study was designed to determine the effect of the consumption of the nutritive sweetener aspartame on non-insulin-dependent diabetics. Forty-three adult diabetics between the ages of 21 and 70 completed a 90-day study; all were diabetics whose conditions were managed by diet and/or hypoglycemic agents. Participants in the blind study were instructed to continue their usual diet and to take two capsules of an assigned preparation three times daily with meals, either the aspartame or the placebo. The 1.8 g of aspartame administered is approximately three times the expected daily consumption of aspartame if used as a sweetener to replace sugar. Throughout the study subjects were examined for (1) symptoms of intolerance, (2) fasting plasma phenylalanine levels exceeding 4 mg/100 ml, and (3) deterioration of diabetic control. At the conclusion of the study subjects exhibited no symptoms that could be traced to the administration of aspartame or the placebo, and diabetic control was unaffected by the chronic administration of these substances. Aspartame seems to be well tolerated by non-insulin-dependent diabetics.