In people with constipation, it is not known if decreased frequency of defecation is associated with abnormalities in the weight or in the consistency of stools or if the weight or the consistency of stools correlates with the severity of various discomforts associated with bowel movements. In neither normal nor constipated subjects has the consistency of stools been carefully correlated with their relative contents of water and solids. Our aim was to gain insight into these questions. Twenty subjects with idiopathic chronic constipation and 20 age- and sex-matched control subjects were recruited by advertisement. Stools were collected for one week. After each bowel movement, the subject's perception of various discomforts associated with the bowel movement were recorded. The stools were then analyzed. The results and conclusions were as follows: (1) Stool weight per bowel movement was similar in the two groups but stool weight per week was markedly reduced in constipated subjects. (2) Reduced stool weight per week in constipated subjects was due to a nearly proportional reduction in stool water and stool solids output. (3) Using data from both groups, there was a curvilinear correlation between percent insoluble stool solids and stool hardness, as measured by a texture analyzer; hardness increased only slightly as percent insoluble solids increased between 7 and 20%, but hardness increased dramatically when percent insoluble solids exceeded 25%. (4) Only 6% of stools from constipated subjects (2 of 34) had abnormally high values for percent stool solids and physical hardness. (5) In subjects with constipation, the severity of various discomforts associated with bowel movements (such as straining) correlated poorly with the weight or the hardness of stool that was produced by the bowel movement.