The effects of corticosterone and ACTH(1–24) on lipoprotein lipase (LPL) activity of rat epididymal fat tissue were studied. Hypercorticism induced by s.c. administration of 10 mg corticosterone acetate for 3 days led to a decrease in LPL activity. This decrease could be prevented by treatment of the rats simultaneously with synthetic ACTH(1–24). Adrenalectomy also reduced LPL activity. Corticosterone and ACTH(1–24) treatment had a similar effect on LPL activity in adrenalectomized and intact rats. These results indicate that ACTH(1–24) may affect adipose tissue LPL in the rat by a mechanism in which corticosterone is not involved. J. Endocr. (1987) 114, 369–372