Non-specific esterases were studied in the epididymis of the bat,C. sphinx sphinx by employing α-naphthyl acetate and 5-bromoindoxyl acetate as substrates and eserine sulphate (10−4 M) as an enzyme inhibitor. The enzyme activity in epididymal cells was diffused cytoplasmic and granular in nature. The granular activity was eserine resistant. Holocrine cells were also observed in the epididymis of this bat. Seasonal variations in epididymal esterases are described.