The sub-chronic (28–56 days) effects of exposure to low concentrations of cadmium (Cd; 0·05, 0·25, 0·50 and 2·50 μg l−1) shortly following fertilization on embryos, larvae and juvenile rainbow trout Oncorhynchus mykiss were examined. Premature hatching occurred at lower concentrations (0·05 and 0·25 μg l−1 Cd), however, delayed hatching was seen in the 2·50 μg l−1 Cd group, with >90% of hatching occurring on the last day of the hatching period. Larval growth was negatively affected by Cd exposure in a concentration-dependent manner. Larvae exposed to 2·50 μg l−1 Cd were 13·9 ± 0·8% shorter in total length (LT) and weighed 22·4 ± 3·5% (mean ±s.e.) less than controls at the end of the exposure period. Plasma sex steroid concentrations (oestradiol in juvenile females and 11-ketotestosterone in juvenile males) were elevated (four- to 10-fold over controls) in exposed fish in both males and females, following 28 days of exposure to 0·05, 0·25 and 0·50 μg l−1 Cd, respectively. These results suggest that environmentally realistic concentrations (in the μg l−1 range) of Cd can affect the development of O. mykiss impacting embryos, larvae and juvenile fish.