We designed a rapid, simple and accurate PCR method to determine sexual identity of mouse fetuses collected on embryonic day 15. A multiplex PCR amplification was used to detect male-specific sequence (Sry) in DNA extracted from fetal livers through SDS denaturation followed by high salt extraction and precipitation. This extraction method resulted in sufficiently purified DNA in < 1 h and was suitable for PCR. The DNA obtained was amplified using a robot thermal cycler for 33 cycles. The reaction was performed in 50 microl, using two sets of primers specific for Sry gene (chromosome Y) and IL3 gene (chromosome 11). Amplification duration was 1.5 h. The assessment of the results was done by electrophoresis in 3% agarose run at high voltage. The 402 bp band (Sry) obtained identifies the male fetuses and the 544 bp product (IL3) confirms the correct amplification of the template DNA. The entire procedure took < 4 h. The specificity of the method was confirmed by fluorescent in situ hybridization using a specific male probe on cultured male and female neural stem cells. This method allowed the preparation and culture of pure male and female neural stem cells from fetal tissue.