In a three-generation reproduction study, groups of ten male and 20 female Charles River CD rats were fed FD & C Blue No. 2 at dietary levels providing intakes of 0.0, 2.5, 25, 75 and 250 mg/kg body weight/day. Slightly bluish-coloured fur was noted in rats at the 250-mg/kg/day dose level and bluish-green-coloured faeces were produced by rats in the 75- and 250-mg/kg/day groups. The gestation, viability and lactation indices of all litters were comparable for the control and treated groups. The fertility indices for female rats in the 2.5- and 25-mg/kg/day groups were significantly lower than those for control females in the case of the F2 litters. However, there was no reduction in the female fertility indices for the F2 litters at the two higher dosage levels, nor for the F1 and F3 litters at any dosage level. Although fertility indices were reduced for some groups of male rats in the F2b and F2c litters, these changes were not considered to be compound-related. Examination of the ovaries and uteri of all dams killed on day 19 of gestation of the F2c and F3c litters revealed no gross anatomical abnormalities. No unusual changes were observed in the stillborn pups or in pups dying during the study. There were no compound-related gross or microscopic pathological lesions in any of the F1 or F3a rats that were killed and necropsied, and no compound-related organ-weight variations were recorded in the F1 parental rats.