Dendritic cells, the primary antigen presenting cells of the human immune system, are heavily infected with human immunodeficiency virus (HIV) in patients with the acquired immunodeficiency syndrome (AIDS). Dinitrochlorobenzene (DNCB) is a contact sensitizing agent that acts as a potent immune modulator of dendritic cells. In this pilot study, we examined the safety and efficacy of topical DNCB application in patients with early HIV disease. Topical DNCB was well tolerated by these patients, with an adverse reaction rate of 10%. CD4+ T-cell counts remained stable with repeated DNCB use. In contrast, CD8+ T-cell counts and natural killer cells increased significantly following DNCB sensitization. This increase in CD8+ T-cell and natural killer cell subsets was accompanied by a decrease in HIV replication, as measured by serum HIV RNA levels. Based on this pilot study, we conclude that topical DNCB is safe in early HIV disease and may decrease viral load via a systemic effect on dendritic cells, CD8+ T-cells and natural killer cells. These results require confirmation in larger controlled trials.