Aim: The aim of the present investigation was to evaluate histologically fibroblastic proliferation on dorsal cutaneous wounds in a rodent model treated or not with light-emitting diodes (LEDs) of three wavelengths. Background: Fibroblasts secrete substances essential for wound healing. There are few reports of LED phototherapy on fibroblast proliferation, mainly in vivo. Animals and Methods: Following approval by the Animal Experimentation Committee of the School of Dentistry of the Federal University of Bahia, we obtained 16 young adult male Wistar rats weighing between 200 and 250 g. Under general anesthesia, one excisional wound was created on the dorsum of each animal; they were then randomly distributed into four groups of four animals each: G0, untreated control; G1, red LED (700 ± 20 nm, 15 mW, 10 J/cm²); G2, green LED (530 ± 20 nm, 8 mW, 10 J/cm²); and G3, blue LED (460 ± 20 nm, 22 mW, 10 J/cm²). The irradiation started immediately after surgery and was repeated every other day for 7 days. Animals were killed 8 days after surgery. The specimens were removed, routinely processed to wax, cut, and stained with hematoxylin/eosin (HE). Fibroblasts were scored by measuring the percentage of these cells occupying the area corresponding to wound healing on stained sections. Results: The quantitative results showed that red LED (700 ± 20 nm) and green LED (530 ± 20 nm) showed a significant increase in fibroblast numbers (p < 0.01 and p = 0.02) when compared with the control group. Conclusion: The use of green and red LED light is effective in increasing fibroblastic proliferation on rodents.