The nuclear transcription factor peroxisome proliferator-activated receptor (PPAR) gamma plays a central role in normal lung development. However, the effects of modulating PPARgamma expression by exogenously administered PPARgamma agonists on lung development and basic blood biochemical and metabolic profiles in a developing animal are not known. To determine these effects, newborn Sprague-Dawley rat pups were administered either diluent or rosiglitazone (RGZ), a potent PPARgamma agonist, for either 1 or 7 d. Then the pups were killed and the lungs were examined for specific markers of alveolar epithelial, mesenchymal, and vascular maturation, and lung morphometry. The effect of RGZ on a limited number of blood biochemical and metabolic parameters was also determined. Overall, systemically administered RGZ significantly enhanced lung maturation without affecting serum electrolytes, blood glucose, blood gases, plasma cholesterol, triglycerides, and serum cardiac troponin levels. The lung maturation effect of PPARgamma agonists was also confirmed by another PPARgamma agonist, the naturally occurring PPARgamma ligand prostaglandin J2. We conclude that systemically administered RGZ significantly enhances lung maturation without significantly affecting the acute blood biochemical and metabolic profiles, providing rationale for further studying PPARgamma agonists for enhancing lung maturation, and for promoting lung injury/repair in neonates.