Objective: Compare the efficacy of light-emitting diode (LED) and therapeutic ultrasound (TUS), combined with a semipermeable dressing (D), at forming collagen in skin lesions by morphometry and Fourier transform infrared spectroscopy (FT-IR). Materials and Methods: Surgical skin wounds (2.5 cm) were created on 84 male Wistar rats divided into four groups (n=21): Group I (Control), Group II (LED), Group III (LED+D), and Group IV (US+D). On days 7, 14, and 21, the tissue samples were removed and divided into two pieces, one was used for histological examination (collagen) and the other for FT-IR. Results: The histomorphometric analysis showed no significant differences among groups for collagen deposition at 7 days. However, at 14 days, more deposition of collagen was noted in the groups LED (p<0.05) and LED+D (p<0.001) than in the control. At 21 days, the groups LED, LED+D, and US+D presented significantly greater deposition of collagen when compared with the control. The FT-IR spectra, at 14 days, LED+D had greater amounts of type I collagen, a better organization of fibers, and greater difference of mean separation between the groups, not observed at 7 and 21 days. Innovation: The histomorphometric and FT-IR analyses suggest that the association of semipermeable dressing to LED therapy and to TUS modulates biological events, increasing fibroblast/collagen response and accelerating dermal maturation. Conclusion: The histomorphometric and FT-IR analyses showed that LED therapy is more efficacious than TUS, when combined with a semipermeable dressing, and induced the collagen production in skin lesions.