Use of organochlorine insecticides, such as 1,1,1,‐trichloro‐2,2‐ bis(p‐chlorophenyl)ethane (DDT), have been banned in most developed countries due to their effects on wildlife populations and their persistence in the environment and foods. However, recently a potential link between exposures to organochlorine insecticides and development of obesity has been reported. Thus, we investigated the role of DDT and DDE (a metabolite of DDT and another organochlorine insecticide) on adipogenesis using 3T3‐L1 adipocytes. Cells were treated with either DDT or DDE (0, 10 & 20 μM) for 6 days of differentiation and markers of adipogenesis were analyzed. DDT and DDE treatments significantly potentiated lipid accumulation and gene expressions of adipogenic factors, CAATT element binding protein‐α (C/EBP‐α), peroxisome proliferator‐activated receptor‐γ, and fatty acid synthase. In addition, leptin and adipose triglyceride lipase (ATGL) mRNA expressions were increased by DDT and DDE. The results suggest that organochlorine insecticides, particularly DDT & DDE, induce adipogenesis via C/EBP‐α mediated pathway.