We studied factors associated with treatment adherence in 88 male and 21 female adults (age range, 24-65 years) with HIV infection undergoing therapy with HIV-1 protease inhibitors (PIs) in Italy. Data on sociodemographic variables, clinical and psychological symptoms, treatment compliance, physician/patient relationship, and psychosocial characteristics were obtained by means of semistructured interviews. Every subject also compiled two self-report questionnaires: Coping Orientations to Problem Experiences (COPE) and Medical Outcomes Study-HIV (MOS-HIV) in order to evaluate the use of coping strategies and quality of life. We found a high rate of adherence to HIV therapies (almost 90% of patients had taken at least 80% of medication in the previous 7 days). No significant differences were found between adherence and nonadherence groups as measured by self-report. Few significant differences were found when data laboratory were used. When a Bonferroni corrected p level of <0.001 was used, only a comparison on Mental Disengagement subscale of COPE was statistically significant.