Objectives: To study the relation between efficacy, safety and plasma concentration of two different brands of lithium carbonate in patients of bipolar disorder. Materials and methods: This prospective, interventional study was done in newly diagnosed patients of bipolar disorder and randomized into two groups, Group A (generic) and Group B (branded generic).Lithium carbonate 300 mg thrice a day given orally in both groups. Data was recorded in pre validated Case Record Form. The Young Mania Rating Scale (YMRS) was measured at baseline and after 3 weeks of therapy. Serum lithium level was carried out on 21st day of therapy. Pearson Parametric Correlation Test and‘t’ test was used for analysis. Results: YMRS was 28 ± 1.07 and 29.08 ± 1.12 (baseline)and 14.04 ± 0.67and 14 ± 0.68(after 3 weeks) in groups A (n=25) and B (n=25) respectively. There was significant mean reduction in YMRS at 2nd follow-up (P< 0.0001). At the end of 3 weeks, the mean serum lithium level in group A and B was 0.68 ± 0.04 and 0.82 ± 0.07 respectively. One patient in each group A and B had low serum lithium level (0.2, 0.26) while 4 patients in group B had high serum lithium level (1.32, 1.32, 1.88 and 1.35). High S. lithium level was associated with increases ADRs. Correlation was significant between increases in lithium level and decrease in YMRS. Conclusions: There is strong correlation between efficacy (YMRS score), and ADRs in both generic and branded lithium carbonate.