The purpose of this study was to assess patient adherence to physician-recommended screening flexible sigmoidoscopy. In the setting of a family practice residency program, adherence rates in asymptomatic patients (N = 333, age > or = 50 years) were compared among a Usual Care Group; an Intervention Group that received educational materials and a phone reminder; and a Continuity Group, which had longstanding continuity with a single physician. Data from mailed questionnaires (N = 180) were used to examine the associations of demographic factors and attitudes with adherence. Adherence was 30.3% overall, with a nonsignificant increase in the Intervention Group compared with the Usual Care Group. In a pooled analysis of the Usual Care and Continuity Groups, the half of the sample with the highest continuity had a significantly higher adherence rate than the rest of the sample (45%; P < 0.001). In a discriminant analysis (78% correct classification, P < 0.001) two history variables (family history of cancer; family history of colon problems), one measure of continuity (number of physician visits), one demographic variable (lower household income), and two attitudinal factors (perception of how painful flexible sigmoidoscopy would be; perception of how well the physician explained its importance) made statistically significant contributions to the prediction of adherence. Results of the study show that screening flexible sigmoidoscopy is acceptable to asymptomatic patients, and that continuity is likely to have a positive impact on adherence. Because attitudes offer the potential for modification, we suggest that physicians reassure patients that flexible sigmoidoscopy is not unduly painful and discuss with patients individually its importance to their health.