To explore potential individual determinants of healthcare utilization in primary care (PC) using a structural equation modelling approach. Atotal of 638 patients from five PC units were randomly selected. Mental disorders, psychological distress and other psychological factors were assessed with the 28-item General Health Questionnaire (GHQ-28) and the Schedules for Clinical Assessment in Neuropsychiatry (SCAN). Medical records and ICD-10 diagnosis were used to measure somatic morbidity. There is a negative relationship between the presence of mental disorders and psychological well-being (-0.74), and a negative relationship with use of health services (-0.25). Age has a positive and significant relationship with the presence of chronic diseases (0.49), which has a positive and significant relationship with limitation of daily activities (0.18). This limitation has a positive relationship with poor perception of health (0.57) and with psychological well-being (0.03). Findings confirm the existence of specific pathways in PC health use. Health service use depends on the patient's psychological well-being and on the presence of chronic medical conditions. Healthcare professionals need to pay attention to the comorbidity of mental disorders and chronic medical conditions in order to identify frequent attenders and to decrease the inappropriate use of healthcare services.