OBJECTIVES: This study assessed gender differences in the frequency of various characteristics of constipation, constipation-specific symptoms, and bowel and dietary habits, as well as the effects of independent but associated risk factors. METHODS: A cross-sectional study of patients aged >or=18 years with a primary diagnosis of constipation (ie, constipation, slow-transit constipation, outlet dysfunction constipation) was conducted at a tertiary referral center; patients were excluded if they had a primary diagnosis of fecal incontinence. Patients completed both a clinical questionnaire to obtain information on demographic characteristics and medical history and an unvalidated self-report questionnaire relating to the characteristics and symptoms of constipation as well as various bowel and dietary habits. Likert scales were used to assess 4 characteristics of constipation (frequency of constipation, duration of constipation symptoms of >or=1 month, bowel movement frequency, stool consistency) and the frequency of occurrence of 6 constipation symptoms (abdominal pain, abdominal bloating, incomplete evacuation, unsuccessful attempts at evacuation, pain with evacuation, straining with evacuation). The bowel habits that were evaluated included time spent at each evacuation; frequency of needing to change position to evacuate; use of anal digitation to evacuate; and the use of laxatives, enemas, stool softeners, foods, drinks, or other aids. The dietary habits that were evaluated included use of dietary fiber, use of fiber supplements, and water intake. RESULTS: Of the 518 patients, the majority were female (79.0%), white (76.3%), and employed (62.0%), with a mean (SD) age of 52.4 (16.5) years (range, 18.6-91.5 years). After controlling for a number of related conditions, women were more likely than men to have infrequent bowel movements (adjusted odds ratio [AOR] = 2.97; 95% CI, 1.67-5.28), abnormal stool consistency (ie, hard or pelletlike stools) (AOR = 3.08; 95% CI, 1.80-5.28), and a longer duration of constipation symptoms (AOR = 2.00; 95% CI, 1.05-3.82). In addition, women were more likely to report an increased frequency of occurrence of abdominal pain (AOR = 2.22; 95% CI, 1.22-4.05), bloating (AOR = 2.65; 95% CI, 1.50-4.70), unsuccessful attempts at evacuation (AOR = 1.74; 95% CI, 1.01-3.00), and the use of anal digitation to evacuate stool (AOR = 3.37; 95% CI, 1.15-9.90). CONCLUSIONS: The women in this specialty-based clinic study experienced a number of constipation symptoms and abnormal bowel habits more frequently than did men. These findings warrant replication in both population- and specialty clinic-based samples. In addition, the physiologic mechanisms that underlie these gender differences warrant investigation.