Occasional constipation is a frequent complaint in medical practice. Bulk-fiber laxatives are often recommended as a safe and effective treatment of this disorder. The viscous suspensions required for administering most bulk-fiber laxatives, however, can negatively affect compliance. This study summarizes physician and patient assessment of a new, oral bulk-fiber laxative caplet following 2 weeks of open-label use for the treatment of constipation and related disorders. Forty-two patients recruited from colorectal surgical practices and who were recommended bulk-fiber as part of their treatment completed the study. Recommended dosage was 2 caplets b.i.d., with each 2-caplet dose providing 1 gram of methylcellulose. Patient diaries reported average daily use of 3.13 +/- 1.20 caplets/day and a total of 577 patient-days of use (calculated as total days product used x number of subjects). Ninety percent of the diaries reported at least one bowel movement daily. Fourteen days of treatment progressively and significantly increased the percentage of complete bowel movements, bowel movements having normal stool consistency, and reduced straining. Physicians rated more than 75% of patients' responses to treatment with methylcellulose caplets as "very good" or "excellent," and considered the responses equal or better than that expected for a fiber treatment in 90% of subjects. Among 24 patients who had previously used fiber, 21 preferred the caplets over prior fiber products. Methylcellulose tablets may provide a useful alternative for improving compliance among patients using fiber therapy.