This study is a long-term prospective, single-blind study comparing biofeedback for pelvic floor dyssynergia to a skeletal muscle relaxant drug (diazepam 5 mg two hours before attempted defecation) and to placebo medication. Prior to randomization, patients will first receive medical therapy (laxatives and education) for 4 weeks and only those remaining constipated will be randomized. Physiological tests of anal canal pressure during straining to defecate and ability to pass a 50-ml air filled balloon will be tested before and after treatment. Patients will keep a diary throughout baseline and treatment, and they will be reassessed at 3, 6, and 12 months follow-up. Treatment will consist of 6 clinic visits at 2-week intervals. The investigators will develop a detailed treatment manual for this disorder which would permit other investigators to replicate their study.