The authors studied 18 adults (8 men and 10 women) in an open trial of nomifensine maleate for the treatment of attention deficit disorder (ADD). All patients met DSM-III criteria and the Utah criteria for ADD, residual type (RT). Medication effect was measured at week 1 and week 4 of treatment using the Structured Interview for ADD-H Symptoms. Data from week 4 showed that all eight men and seven of the women responded well to nomifensine, showing a significant decrease in ADD with hyperactivity symptoms. Side effects were minimal, consisting of drowsiness, dry mouth, headache, and nausea. One responder (5%) was taken off the medicine after developing an allergic reaction. Results showed that short-term use of nomifensine was relatively free from side effects and was remarkably effective in the treatment of ADD-RT. The authors discussed the implications of the use of nomifensine and related drugs in the treatment of ADD-RT.