The toxicity of total residual chlorination (TRC) to early life stages of the striped bass, Morone saxatilis, was determined using percent embryo hatchability, incipient LC50 bioassays, histopathology, and avoidance responses. Beginning 8 to 9 hours after fertilization, developing embryos were exposed continuously to TRC in flowing water at 1,0-3.0 ppt salinity and 18 plus or minus 1 C. Fifty-six percent of the control group (no TRC exposure) hatched. None of the embryos exposed to a measured TRC concentration of 0.21 micrograms/l hatched. Only 3.5 percent of the embryos exposed to 0.07 micrograms/l TRC and 23% of those exposed to 0.01 micrograms/l hatched. Incipient LC50 bioassays were used to determine sensitivity of 2-, 12- and 30-day-old striped bass to concentrations of TRC in flowing water (1.0-3.0 ppt salinity at 18 plus or minus 1 C). The estimated incipient LC50 was 0.04 micrograms/l TRC for 2-day-old prolarvae, 0.07 micrograms/l for 12-day-old larvae and 0.04 microgram/l for 30-day-old juveniles.