To estimate the levels of underreporting of medical visits and to compare the reporting of chronic restrictive diseases, 203 individuals who had been visited in a Primary Health Center were interviewed in the period of two weeks following the medical visit. Underreporting of a medical visit was identified in 31 (15.3%) of the users. The level of underreporting was not related with age, sex, education or socioeconomic status. Reporting of chronic restrictive illness was compared with the information recorded in the user's medical record. The highest global agreement (91.6%) was observed for hypertensive disease (kappa index = 0.71), while the lowest agreement was found for chronic back pain (global agreement = 77.8% and kappa index = 0.14). Since underreporting of medical visits was moderate, the results suggest that this question can be used for the analysis of social differences in the access to health services. Nevertheless, estimation of the prevalence of chronic limiting conditions in a health interview survey should be done with great caution.