Quantity and concentration of sperm production is of fundamental importance for artificial insemination. The knowledge of the repeatability of these characters is useful as a preliminary trait for establishing programs of genetic and/or management improvement. Seventeen Muscovy duck males of a local Italian variety were tested during the entire reproductive season. repeatability of part record of sperm production was evaluated in different periods and correlation coefficients were calculated between periods within animals. Results showed that repeatability is sufficiently high but correlation coefficients and Spearman rank correlation coefficients between part-records are quite low.