Minerals and micronutrients deficiency have been reported to impair reproductive function. We investigated the influence of low salt diet and high salt diet on implantation and pregnancy in Sprague-Dawley rats. One hundred and forty-four rats were acclimatized and divided into three groups consisting of control/normal salt diet (0.3% salt), low salt diet (0.14% salt) and high salt diet (8% salt). All the rats were fed with respective diets for 6 weeks. The oestrous cycle was then monitored daily and on the evening of proestrus male rats were introduced for mating. Mating was confirmed by the presence of sperm cells in the smears the following day and was taken as day one of pregnancy. Implantation studies were carried out on days 6 and 8 of pregnancy while foetal parameters were ascertained on day 19 of pregnancy and at term. Levels of progesterone, oestradiol, prostaglandin E2, nitric oxide (NO) and cyclic guanosine monophosphate (cGMP), were measured on days 6, 8 and 19 of pregnancy. The results showed decreased implantation sites on days 6 and 8 in high salt fed rats, decreased birth weight in low salt fed rats and increased placental to birth weight ratio in the high salt fed rats when compared with control. A significant decrease in PGE2 level was found on day 8 of pregnancy in the high salt fed rats, while progesterone: oestradiol ratio was decreased on days 6 and 8 of pregnancy in both low salt and high salt fed rats. Also, NO and cGMP levels were decreased on day 19 of pregnancy in the low salt fed rats when compared with control (P<0.05). The results showed that a shift in salt homeostasis either to a high or a low salt level causes hormonal imbalance, impaired implantation and pregnancy outcome.