Adipose triglyceride lipase (ATGL) is a newly identified lipase. We report for the first time the porcine ATGL sequence and characterize ATGL gene and protein expression in vitro and in vivo. Adult pig tissue expresses ATGL at high levels in the white adipose and muscle tissue relative to other tested tissues. We show that within the white adipose tissue ATGL is expressed at higher levels in the adipocyte than in the stromal-vascular fraction. Additionally, ATGL expression increases dramatically in the subcutaneous adipose during adipose development and maturation, as well as during in vitro adipogenesis. Peroxisome proliferator-activated receptor gamma transcript levels increased concomitant with ATGL gene expression, suggesting a possible role in the regulation of ATGL by adipogenic regulators. In vitro treatment of differentiated primary pig preadipocytes with insulin and forskolin decreased ATGL gene expression in a dose-dependent manner, suggesting ATGL transcript levels are hormone sensitive. In vivo experimentation showed that calorie-restriction in gilts resulted in increased ATGL mRNA and protein levels in subcutaneous and peri-renal fat tissues. Our data demonstrate that ATGL expression reacts to hormonal stimuli and plays a role in catecholamine-induced lipolysis in porcine adipose tissue.