Background: Obesity is a major risk factor for the development of chronic diseases and mortality. At the cellular level, increasing number and size of adipocytes diferentiated from preadipocytes characterized the obesity. Excess intake of sugars and lipids causes obesity, but certain food components have been reported to reduce the risk of obesity. Catechins, the active constituent of green tea has been regarded beneficial as an anti-obesity. Our previous study has showed that catechins from green tea GMB4 clone inhibited differentiation of preadipocytes, reduced PPARy and increased the adiponectinn level in preadipocytes culture (Ratnawati et al, 2011) and EGCG also decreased C/EBPα and leptin (Ratnawati et al, 2012). Therefore in this study, we investigated the effect of catechins on the positive and negative regulators of lipogenesis and adipogenesis; ROR-α and C/EBP-α. Method: This study is done in primary cultured of preadipocyte with 4 groups of treatment : (1) control, (2) treated with catechins 5 µM, (3) treated with catechins 10 µM and (4) treated with catechins 30 µM. 2 days post confluence, cell were induce to differentiate into adipocyte with IBMX, DEX and insulin. On days 3 during differentiation, cells were treated with catechins for 24 hour. Cells then harvested and measurement of ROR-α and C/EBP-α were done by ELISA and Immunocytochemistry. Results: In this study we found that catechins significantly reduced the expression of C/EBP-α by 20%, 24% dan 26,43%. . We found that ROR-α expression increased, but not reach statistical significance. Conclusion: This results suggested that catechins at least in part inhibit adipogenesis through C/EBP-α. Studies are needed to see whether higher doses of catechins will exert further increase on ROR- expression and/or its activity.