Objective: To investigate the effect of lithium (Li) on some aspects of reproductive physiology, comprising of luteinizing hormone (LH) activity and changes in the maternal behaviour of albino rat. Methods: Oestrous cycle, receptivity of female rat on the days of oestrus and incidence of mating confirmed by presence of sperm in vaginal smear were studied. Rats with sperm positive vaginal smear were isolated and observed for pregnancy state. The maternal behaviour was assessed by behaviour profile of lactating mother. Simultaneous measurement of Li concentration in brain and serum and level of circulating luteinizing hormone (LH) were carried out to indicate the involvement of endocrine vis-a-vis neuronal correlates. Results: A significant delay in normal oestrus, reduced number of foetuses, difficult labour, maternal indifference to litters and cessation of nursing were associated with observation of reduced circulating LH level and with accumulation of Li in brain and serum. Conclusion: Changes in the reproductive behaviour associated with reduced levels of circulating LH were correlated with the presence of Li ion in brain and plasma.