Samples of American sand lance (Ammodytes americanus) were collected in JuneSeptember 1983 off the north shore of the Gulf of St. Lawrence, at depths varying from 1 to 40 m. Length-frequency modes identified by modal analysis corresponded closely with mean lengths of fish based on otolith annuli counts, supporting the hypothesis that the number of annuli corresponds to the age of the fish. The otolith length was linearly correlated with the fish length. An opaque annulus was deposited over a short period, primarily August. The study indicated that 75-100% of the annual growth was achieved during the June-September period. Maximum life span was estimated to be 12 years. The parameters of the von Bertalanffy growth equation were: K = 0.24 year", Lao = 188.2 mm, to = -1.14 year. The growth of the American sand lance in the study area was slower than for the same species and for A. dubius in more southern areas. The length-weight relationship indicated that the growth in weight was isometric and identical for both sexes. Length-weight relationship, gonadosomatic index and the observation of maturity stages suggested that reproduction takes place shortly after September. All the fishes were matured at 20 months of age. Males mature at a smaller size «85 mm) than the females (90 mm).