Exposure to maternal obesity or overfeeding during early development has lasting effects upon the young adult rat. Maternal cafeteria (CD) feeding during lactation programmes behaviour in the adult offspring, reducing anxiety in males and altering the behavioural satiety sequence in females. The aim of the present study was to examine the impact of early exposure to maternal over-nutrition upon bioactive amines in the brain. Lactating Wistar rats were fed either a control chow (n=5) or CD (n=5). CD consisted of a range of highly palatable human food items, high in fat and sugar (including cheese, pate, pork-pie, peanut, chocolate, crisps and shortbread). At weaning all offspring were transferred to the control diet. At 20 weeks of age offspring were culled and the hypothalamus, hippocampus and frontal cortex were dissected. 5-HT, 5-HIAA, DA, DOPAC and HVA concentrations were measured using HPLC. Exposure to CD during the suckling period had little effect upon body weight and adiposity of the offspring, although CD females had 39% more perirenal fat than controls (P<0.001). Hypothalamic concentrations of 5-HT were increased by 33% in both male and female CD offspring (P<0.01). In these animals, 5-HT turnover was significantly reduced (37%) in the hypothalamus (P<0.0001). In CD females, DA concentrations were increased (37%, P<0.05) and DOPAC concentrations were reduced (38%, P<0.05) in the hypothalamus. Hypothalamic DA turnover was significantly decreased in both male (31%, P<0.01) and female (22%, P<0.01) CD offspring. There was no effect of maternal diet upon 5-HT or DA turnover in the hippocampus or frontal cortex. The present findings suggest early life programming of hypothalamic 5-HT and DA turnover in response to maternal over-feeding. The data is suggestive of a role for these neurotransmitters in determining the altered behaviour of such animals.