Abstract Background Successful treatment of HIV-positive children requires a high level of adherence (at least 95%) to highly active antiretroviral therapy. Adherence is influenced by factors related to the child and caregivers. Objectives To evaluate children and caregivers characteristics associated to children's adherence. Methods Cross-sectional study, from September 2013 to June 2015, comprising a sample of caregivers of perinatally HIV-infected children, in the age group of 1–12 years, under antiretroviral therapy for at least 6 months and on follow-up in two AIDS reference centers in Salvador, Bahia. Caregiver self-reports were the sole source of 4 days adherence and sociodemographic information. Study participants who reported an intake >95% of prescribed medication were considered adherents. A variable, (“Composed Adherence”), was created to better evaluate adherence. Results We included 77 children and their caregivers. 88.3% of the caregivers were female, the median age was 38.0 years (IQR 33.5–47.5), 48.1% were white or mixed, 72.7% lived in Salvador and 53.2% had no fixed income. The 4 days child's adherence was associated only to caregivers that received less than a minimum salary (p < 0.05), 70.1% of the caregivers had less than four years of formal education, 81.8% were children's relative and 53.2% of the caregivers were HIV positive. The caregiver's pharmacy refill, long-term adherence and 4 days adherence, were significantly associated with composed adherence (p < 0.05). Child's long-term adherence was strongly associated to the 4 days child's adherence referred by caregiver (p < 0.001). Conclusions Our results suggest the need of improvement in HIV-infected children adherence, through reinforcement of the caregivers own adherence.