We prospectively evaluated 38 patients with chronic severe idiopathic constipation who failed to respond to conventional therapy. Colonic transit studies, the Hopkins Symptom Checklist (SCL-90-R), and the Minnesota Multiphasic Personality Inventory (MMPI) were completed. Colonic transit studies identified 23 patients with slow transit and 15 with normal transit. Patients with normal transit constipation scored higher than those with slow transit on every scale of both the SCL-90-R and MMPI, but the SCL-90-R appeared to detect greater differences between the two groups. We conclude that the SCL-90-R is the preferred psychological instrument to evaluate patients with chronic severe constipation who fail to respond to conventional therapy. It provides information similar to the MMPI with which to measure behavioral profiles of patients in an office setting, and it can be completed and scored more rapidly.