In this study, the susceptibility of mature human oocytes to HIV-1 infection has been investigated. We exposed in vitro human oocytes of healthy women using inocula of cell-free HIV-1. We also tested for the presence of HIV-1-specific receptor molecules on the surface of these cells. By applying polymerase chain reaction (PCR) analysis, transmission electron microscopy (TEM), and immunocytochemistry at both light and electron microscopic levels, we did not obtain evidence for HIV DNA production nor for oocyte-associated HIV particles. Experiments of immunostaining for CD4, CCR5, and GalAAG (putative receptor for HIV in sperm), as well as reverse transcriptase (RT)-PCR for CD4, CCR5, and CXCR4, which all suggested the absence of the mentioned receptors in mature oocytes and in follicular cells. This study fills an important gap concerning the information available on the direct HIV infection of human gametes, adds to our basic understanding of HIV infection in human oocytes, provides different results from those obtained with human spermatozoa using comparable methods, and provides a basic contribution to the investigation on HIV infection in human oocytes.