This paper reports 39 cases of manic patients treated with lithium carbonate or lithium carbonate plus chlorpromazine. Levels of plasma lithium, sodium and potassium, erythrocyte lithium and lithium ratio -were determined when the blood lithium had reached the steady state and continued 4 weeks of treatment respectively. The mean duration of ditcontinuing chlorpromazine at the second time of determination in the combined drug group was 17?8.5 days.We found most lithium treated patients (83%) who got improvement or remission showed elevation of their lithium ratio. On the average, chlorpromazine can increase the erythrocyte lithium by 31 % and lithium ratio by 20%. Plasma lithium, erythrocyte lithium and lithium ratio were in positive correlation. Sex, family history, Plasma sodium and potassium level showed no correlation with their lithium ratio