Summary.Changes in the localization of sperm surface glycocomponents of testicular, epididymal, vas deferens, and ejaculated spermatozoa of dog (Canis domesticus) were studied employing fluorescein isothiocyanate conjugated lectins viz., Concanavalin A (ConA), Triticum vulgaris (WGA), Maclura pomifera (MPA), and Arachis hypogaea (PNA) agglutinins. The plasma membrane clothing the acrosome of the testicular, epididymal, and vas deferens spermatozoa shows reactivity with all the lectins used. However, in the ejaculated spermatozoa, the entire sperm surface shows reactive sites for ConA, WGA, and PNA. Variation in the labelling of the cytoplasmic droplet in different stages of spermatozoon transit in the epididymis has been discussed.