The purpose of this investigation is to build on the findings of earlier studies and, focusing on specific disease categories, further explore the factors which may contribute to the sex differential in medical care utilization rates. In pursuing this objective, the study attempts to differentiate those types of disease categories for which illness orientation has a significant effect on utilization rates from those where the effects are minimal. The study population includes 1648 adults between the ages of 18 and 59. Medical record data covering 7 years of outpatient services are linked with survey data on the respondents. The findings show that the largest sex differences in utilization rates occur in those categories which represent more mild morbidities and those where there is more discretion in defining illness and/or the need for care. It is in these categories showing the largest sex differences in doctor office visits in which illness orientation factors appear to be most influential. Thus, the findings provide further evidence for the hypothesis that sex differences in morbidity reports and utilization rates are due to differences in the way symptoms are perceived, evaluated and acted upon. Interpretations and implications are discussed.