The growth of northern pike (Esox lucius) in Lake Thompson, South Dakota was assessed seasonally over a two-year period. Northern pike were short-lived; the oldest fish collected was age 8. Female northern pike lived longer than male fish, and mean length-at-age was significantly higher for females than for males. Significant increases in mean body length occurred during cool- and cold-water seasons, but no increases in mean length were found for either sex from July through August, which was the period of highest water temperature. Incremental growth in length (mm/d) for male northern pike was related to water temperature, with maximum growth rates occurring in the range of approximately 8–18°C.