Introduction Cancer of the prostate in HIV-infected patients has rarely been reported in the literature. Observation A 40 year-old man presented with an adenocarcinoma of the prostate and bone and glandular metastases. The patient exhibited HIV seropositivity stage B1, the immune-virology of which was well controlled by antiretroviral tritherapy. Comments The relationship between cancer and HIV has been established for certain cancers such as Hodgkin's disease, non-Hodgkin malignant lymphoma, Kaposi's sarcoma and invasive cancers of the uterine neck in women. The significant increase in some cancers in patients infected by HIV (lung, penis, soft tissue, lips, seminoma) suggests the potential association with immunodepression unless it corresponds to a risk induced by antiretroviral treatments in the long term.