A 47-year-old architect and a 30-year-old designer of audio goods presented with thrombosis of left and right posterior scrotal vein, respectively. Both had scrotal masses associated with a feeling of heaviness. Physical, operative and microscopic findings were similar. The lesions were palpated as nontender, slender, elastic masses and located parallel to the urethra in the posterior aspect of the scrotum. At surgical exploration the lesions appeared to be thrombosis of posterior scrotal vein and were removed. Both patients have remained well one year in one and four months in the other after operation. Pathological diagnosis for both surgical specimens was organized thrombosis of vein with eosinophilic infiltration. Eosinophilic infiltration to lesions in the present cases and the occupation of patients suggested that some immunological disorders and localized venous stasis for long time during their sitting work might relate to the formation of thrombosis in the posterior scrotal vein. To our knowledge this is the first report of thrombosis of the posterior scrotal vein.