Concentrations of adiponectin are inversely related to obesity-related diseases, and adiponectin regulation is not completely understood. N-3 polyunsaturated fatty acids are known ligands for peroxisome proliferator-activated receptor-[gamma] (PPAR[gamma]), a key transcription factor for the adiponectin gene. The objective of this study was to examine the regulation of adiponectin by eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) 'in vitro.' 3T3-L1 adipocytes were incubated with 125 [mu]M EPA, DHA, palmitic acid or oleic acid complexed to albumin, or with albumin alone (control). After 24 h, media was collected for analysis of secreted adiponectin and RNA was isolated for analysis of adiponectin and PPAR[gamma] mRNA expression. Both DHA and EPA significantly increased ('P' < 0.05) the amount of secreted adiponectin compared to control (102% and 44%, respectively). Interestingly, only DHA enhanced mRNA expression of adiponectin and PPAR[gamma] (' P' < 0.05). Our results demonstrate that DHA may upregulate adiponectin production through PPAR[gamma] activation.