Abstract Introduction Anorectal physiology tests are indicated for patients who have refractory symptoms of constipation, but the best sequence of investigation remains controversial. Objective To evaluate the influence of colonic transit time and anorectal manometry in the diagnosis of chronic constipation in adults. Method This was a study of adult patients with constipation at a private clinic in a city in southern Brazil, from January 1, 2009 to December 31, 2018. Those who showed warning signs were referred for colonoscopy and those with any anatomical alterations were excluded. The patients received 10 g of psyllium and those who remained symptomatic after three weeks were referred for functional assessment with colonic transit time (CTT). Those who presented outlet obstruction in the colonic transit time were referred to anorectal manometry. Results Of the 889 adult patients surveyed, 227 were included. Of the 216 who completed the study, 167 responded to primary treatment. Forty-nine underwent CTT. In these, 16 had normal colonic transit time and 33 were altered. In those with altered colonic transit time, eight had a pattern of colonic inertia and 25 had an obstruction pattern. The 25 patients with an outlet obstruction pattern underwent anorectal manometry. Eighteen had signs of paradoxical contracture of the puborectal muscle (PPRC) and seven did not. Conclusion This study concluded that anorectal physiology exams contribute to the diagnosis of constipation, often changing the behavior. These exams should be performed whenever the patient does not respond to hygienic changes and fiber replacement.