Adipose tissue alterations (ATA), which are common among persons treated with highly active antiretroviral therapy (HAART), can have substantial psychologic repercussions, with a subsequent negative impact on the patient's quality of life and on HAART adherence. However, the cross-sectional nature of the studies precludes establishing the direction and causality of the relationship. The authors evaluated the longitudinal relationship between ATA and adherence to HAART. The analysis included all participants in the AdICoNA and the LipolCoNA substudies of the Italian Cohort Naive Antiretrovirals (ICoNA). Adherence was assessed using a 16-item self-administered questionnaire, which also included a question on self-perceived fat accumulation experienced during the past 4 weeks. ATA was diagnosed by physicians at enrollment and evaluated every 6 months thereafter. There were 207 patients, with a median age of 35 years; 73% were men; and 34% acquired HIV through injection drug use. At baseline, nonadherence was reported by 63% of participants, and ATA was self-perceived by 15% and clinically diagnosed in 25%. Using Cox regression analysis, patients with good adherence at baseline were more likely to develop ATA (RH = 2.58; 95% CI, 1.09-6.11) and developed it sooner. Self-perceived ATA at baseline was independently related to subsequent nonadherence (OR, 4.67; 95% CI, 1.01-22.4), but clinically diagnosed ATA was not (OR, 0.77; 95% CI, 0.37-1.61). Patients' adherence to HAART is a dynamic process that interacts with ATA. Better adherence is associated with a higher risk of subsequent occurrence of ATA, while patient-perceived onset of morphologic alterations can reduce adherence to antiretroviral therapy.