HIV-1 infected patients who meet inclusion and exclusion criteria will be enrolled for screening. Stool samples will be collected at enrollment and evaluated for ova and parasites. All patients who are found to have positive stool parasite examinations and who consent to participate will be enrolled in the treatment phase of the study. Those who are found to have negative stool specimens will not continue to the treatment phase. Baseline demographic and socio-economic data will be collected from these patients in order to evaluate the prevalence and correlates of helminth infection among HIV-1 infected individuals. Those who are found to be infected with helminths but who decline to participate in the treatment phase will be treated at no charge with a three day course of albendazole (400 mg/day) by the study investigators. Those patients who are enrolled in the treatment phase will have blood collected for baseline plasma HIV-1 RNA levels. Computer-generated random number allocation will be used to assign treatment group. The pharmacy at the Kenya Medical Research Institute will be responsible for the determination of randomization group and distribution of albendazole and placebo. The pharmacy will also be responsible for maintaining records regarding treatment group. Treatment will be provided in the form of a six 200 mg pills of albendazole or six placebo pills identical in appearance. Both placebo and albendazole will be provided in an identical appearing envelope. Treatment arms consist of either initial therapy with albendazole (400 mg per day for three days) or two placebo pills per day initially. All patients will be required to visit the clinic twelve weeks after enrollment. At this twelve week visit, stool samples will again be collected for evaluation of helminth infection. Plasma CD4 count and HIV-1 RNA level measurements will be repeated at this twelve week visit. All patients who received placebo initially as well as all patients with evidence of helminth infection will be treated with open-label albendazole therapy regardless of initial treatment arm. At enrollment and the twelve week visit, lymphocytes will also be isolated from serum samples for assessment of immune activation markers. Genital HIV-1 RNA levels will be compared in 100 individuals randomized to immediate versus deferred antihelminthics at baseline and at the 3-month visit (prior to receiving deferred therapy). This will provide data quantifying the potential effect of anti-helminthic treatment on genital HIV-1 RNA. Consenting adults will have genital swabs collected (semen or cervical/vaginal) and placed in freezing media prior to cryopreservation and transport to Fred Hutchinson Cancer Research Center for HIV-1 RNA assays.