BACKGROUND: Vascular endothelial growth factor (VEGF) and its receptor fms-like tyrosine kinase-1 (Flt-1) have a very important position in the field of male reproduction. However, it is still unclear about their expression meaning and regulatory mechanism in the reproductive system. OBJECTIVE: To study the expression and location of VEGF and Flt-1 in the epididymal sperm of adolescent male rats. METHODS: The expression of VEGF and Flt-1 was detected in 10 adolescent SD rats. The concentration of the sperm was (30-40)×109/L. Immunofluorescent staining was used for VEGF and Flt-1 expression and location in the sperm. RESULTS AND CONCLUSION: Immunofluorescent staining showed that VEGF and Flt-1 were both localized in the acrosome of sperm head, as well as in the neck, middle and principal segment of sperm tail. Specific expression patterns of VEGF and Flt-1 in the sperm of rats display that they may participate in spermiotelcosis, relevant to movement, capacitation and acrosome reaction of the sperm.