ObjectivesTo evaluate the impact of response to highly active antiretroviral therapy (HAART) on the natural history of AIDS non-Hodgkin's lymphoma (NHL) and to analyse the feasibility, efficacy and toxicity of HAART in combination with chemotherapy.DesignProspective observational study in two AIDS clinical centres in Italy.MethodsAll consecutive HIV-infected patients with NHL were included (n = 44; 48% high-risk group) and prospectively followed for 27 months. HAART was administered concomitantly with chemotherapy. The association between response to HAART and clinical presentation, response to chemotherapy and toxicity was analysed by univariate and multivariate models. Survival analysis was performed by Kaplan–Meier estimates and the Cox proportional hazards regression model.ResultsA complete response (CR) to chemotherapy was achieved in 71% of HAART responders and 30% of non-responders. Virological response to HAART was the only variable associated with tumour response on multivariate analysis. A higher relative dose intensity (RDI) of chemotherapy was administered in patients with virological response compared with those without. The probability of 1 year survival was higher in patients with virological or immunological response. At Cox regression analysis, immunological response, a higher RDI and a CR to chemotherapy were all associated with a reduced risk of death.ConclusionIn HIV-infected patients with NHL, response to HAART was strongly associated with a better response to chemotherapy and prolonged survival. Concurrent treatments were well tolerated, and HAART-responder patients could receive a higher RDI of chemotherapy. In patients with AIDS lymphomas, combining HAART with chemotherapy could be a feasible and effective approach.