A case-control study was conducted that involved a retrospective chart review of 181 HIV-infected women in whom cervical dysplasia had been diagnosed to examine the association between patient adherence to highly active antiretroviral therapy and the regression or stabilization of cervical dysplasia. Patient adherence to the medical regimen was evaluated using prescription refill data. Analyses of 154 case patients and 27 control patients showed that adherence to antiretroviral therapy was associated with changes in cervical dysplasia. Patients who were more adherent to treatment showed the greatest regression and the least progression of dysplasia, while those who were least adherent to treatment showed the greatest amount of progression and the least regression.