Striped bass eggs, 24 hours after fertilization, and newly-hatched fry were tested to determine their sensitivity to zinc and copper. This study with those of Hughes will provide information on the most sensitive stage ofthesefish to acute exposure to lethal levels of zinc and copper. Newly-hatched fry were more sensitive to both zinc and copper than were eggs, but copper, at the lowest concentration used, retarded hatching. Eggs and fry were more sensitive to copper than to zinc. In order for acute toxicity studies to have a predictive value, confidence limits need to be placed on the TLm values obtained from toxicity studies. Results obtained from three different methods of providing confidence limits are discussed and the relative merits of each method are compared.