This study was designed to assess the various subtypes of functional constipation in a referral gastrointestinal center of a Latino-American country. All patients referred for evaluation of constipation during a 10-year period were audited, and those with functional constipation according to Rome I criteria classified by physiologic tests of colonic transit, as well as tests of anorectal and pelvic floor function. More than 70% of patients with functional constipation had evidence of pelvic floor dysfunction, whereas those with slow transit and constipation-predominant irritable bowel syndrome subtypes were less frequently represented. Even in a setting different from those most frequently reported in the literature, pelvic floor dysfunction represents the most common cause of functional constipation. Simple, physiologic testing is needed and useful for the diagnosis. This fact has therapeutic implications, especially because many such patients may benefit from biofeedback.