Background: Recent studies indicate that light-emitting diodes (LED) may represent a novel and effective anti-aginglight source for the skin. Among many candidate molecules known to control collagens, caveolin-1 (Cav-1) is knownto play an inhibitory role in cutaneous collagen metabolism. Objective: This study aimed to evaluate the effects of LED irradiation on the expression levels of Cav-1 andprocollagens (proCOLs) in human dermal fibroblasts (HDFs). Methods: Cultured HDFs were irradiated with 630 nm LED at different doses, and the mRNA and proteinexpression levels of Cav-1 and proCOLs I/III were analyzed. Results: In LED-irradiated HDFs, mRNA and protein levels of Cav-1 were found to be down-regulated, whereasthose of proCOLs I/III were up-regulated in a dose-dependent manner. A negative correlation between Cav-1 andproCOLs was verified in Cav-1 siRNA transfected HDFs. LED was moreover found to result in up-regulation oftransforming growth factor (TGF)-β1 and its receptors (TβRI, TβRII), SMAD1, and SMAD2 mRNA levels,indicating that LED may activate the TGF-1/TβR/SMAD pathway in HDFs. Conclusion: The anti-aging effects of 630 nm LED on human skin are likely mediated by up-regulation of proCOLsI/III and inhibition of Cav-1 expression levels in HDFs.