The movements of age‐II and older striped bass (Morone saxatilis), tagged during 1976 and 1977 within a 70‐km section of the lower Hudson River, were determined from recaptures of fish within and outside the river. Movements within the river prior to and during the spawning period are related to maturity, age, and sex. During March and April, mature and immature fish coexist downriver from the principal spawning grounds. By late April, immature fish tend to migrate downriver and mature fish upriver. Males precede females to the spawning grounds. Following spawning, most striped bass leave the Hudson River and move generally northeast‐ward in Long Island Sound and the Atlantic Ocean, but the majority are restricted to within 50 km of the river mouth. There is no correlation between distance moved and fish size, sex, or age. The migratory patterns of striped bass within the Hudson River system contrast markedly with those in the Chesapeake Bay system.