Primary Health Care is essential health care based on delivering integrated health services (curative and preventive). The Kingdom of Saudi Arabia adopted this approach in 1980, and by the year 1987 the Ministry of Health had established 1477 Primary Health Care centers. The expansion in Primary Health Care created a need for various types of evaluation. Theorists recommended the study of patients' satisfaction as a way of evaluating care. The aim of this study was to assess the satisfaction of patients with different aspects of Primary Health Care services in Riyadh. The sample consisted of 300 patients chosen systematically from three Primary Health Care centers in Riyadh. The data were collected by personal interviews. The tool consisted of demographic data, a 4-point rating scale of 40 statements measuring satisfaction with different aspects of Primary Health Care services, and an open question eliciting the patients' suggestions for improvements. The analysis of variance (ANOVA) was used to determine the difference in level of patient satisfaction between the three centers. The results show that the patients were moderately satisfied with the services. They were most satisfied with the effectiveness and humane aspects of care, and least satisfied with the thoroughness and continuity aspects of care. It is recommended that the Ministry of Health develop programs for its personnel to sensitize them to the different aspects of Primary Health Care.