Pharmacological agonists for the nuclear receptor PPARγ enhance glucose disposal in a variety of insulin-resistant states in humans and animals. The precise mechanisms whereby activation of PPARγ leads to increased glucose uptake in metabolically active cells remain to be determined. Notably, certain novel, synthetic PPARγ ligands appear to antagonize thiazolidinedione-induced adipogenesis yet stimulate cellular glucose uptake. We have explored the molecular mechanisms underlying the enhancement of glucose uptake produced by PPARγ agonists in 3T3-L1 adipocytes. Rosiglitazone treatment for 48 h significantly increased basal and insulin-stimulated glucose uptake and markedly increased the cellular expression of GLUT1 but not GLUT4. Rosiglitazone increased plasma membrane levels of GLUT1, but not GLUT4, both basally and after insulin stimulation. Surprisingly, adenoviral expression of a dominant-negative mutant PPARγ, which was demonstrated to strongly inhibit adipogenesis, completely failed to inhibit rosiglitazone-stimulated glucose uptake. Similar findings were obtained with the non-thiazolidinedione PPARγ agonists, GW1929 and GW7845. The insensitivity of PPARγ agonist-stimulated glucose uptake to expression of a dominant-negative mutant, compared with the latter’s marked inhibitory effects on preadipocyte differentiation, suggests that, as is the case for other nuclear receptors, the precise molecular mechanisms linking PPARγ activation to downstream events may differ depending on the nature of the biological response. The growing evidence that the effects of PPARγ on adipogenesis and glucose uptake can be dissociated may have important implications for the development of improved antidiabetic drug treatments.