Since 1958, the National Disease and Therapeutic Index (NDTI) has provided annual statistics summarizing the frequency physicians throughout the United States are visited for different disease conditions. In our present study, these data were used to examine the epidemiology of constipation. Since NDTI statistics are available for a longer time period than other U.S. statistics, they might confirm or disprove the relevance of recent environmental changes on the occurrence of this disorder. The average number of physician visits for constipation in the United States was 2.5 million per year, corresponding to a prevalence of 1.2%. The largest number of these patients (31%) was seen by general and family practitioners, followed in declining order by internists (20%) and pediatricians (15%). Only 4% of all these patients was seen by gastroenterologists. Eight-five percent of these patients received a prescription for medication, with laxatives and cathartics being the most frequently prescribed drugs. Among physician visits for constipation, female prevalence was 1.6% compared with 0.8% for males (P less than 0.001). In both sexes, there was a significant age-related increase in the rate of physician visits, with the steepest rise from 1.3% to 4.1% occurring between the age groups 60-64 and over 65. From 1958 to 1986, the rate of all physician visits for constipation remained unchanged. However, during this time period, there was a twofold rise in physician visits for those patients ages 0-9 years, while a smooth decline occurred in all of the older age groups.(ABSTRACT TRUNCATED AT 250 WORDS)