Reproductive ageing in female rodents is accompanied by changes in circulating peptide and steroid hormones leading to irregular, lengthened oestrous cycles prior to loss of fertility. In this study, the effect of ageing is reported on steroid hormone synthesis within individual ovarian follicles and its retardation by restricted feeding for two groups of ad libitum fed animals (114 and 350 days) and two groups of diet-restricted animals (350 and 600 days). Follicles from ad libitum fed animals of 350 days showed a transition in follicular steroid hormone synthesis to release elevated amounts of oestradiol-17beta on all days of the cycle. This age-related change in follicle steroid release was significantly delayed by maintaining animals on a restricted feeding regime, and was not complete even by 600 days of age. This effect of diet as a means to manipulate ageing of the follicular steroidogenic pathways provides a useful system for investigating the control of reproductive ageing in rodents.