Taking antiretrovirals once-a-day is considered the simpler way to improve adherence. However, it is not know if this assertion apply to patients taking their medication twice-a-day who change to once-a-day.

We hypothesized that once-daily dosing improves adherence.

Inclusion Criteria:

• HIV-1 infected adults receiving antiretroviral therapy including nevirapine twice-a-day for at least 6 months
• plasma HIV RNA<400 cp/ml during the previous 4 months on 2 occasions
• accept adherence electronic monitoring
• written informed consent signed

Exclusion Criteria:

• asparate aminotransferase (AST) or alanine aminotransferase (ALT) >2.5N if hepatitis virus B or C were negative
• AST or ALT>1.25N if hepatitis virus B or C were positive