Dimethyl sulfoxide (DMSO) is an anti-inflammatory, antibacterial, analgesic drug widely used to treat several diseases as reported in the literature. It has a detractive effect on collagen deposition in the abnormal tissue. This study aimed to investigate the possible therapeutic effects of DMSO on hypertrophic scar formation in rabbits. Twenty-four New Zealand male albino rabbits were randomly divided into four groups: control, sham, DMSO, and TRA (triamcinolone acetonide). Except the control group, punch biopsy defects were created on each animal's right ear. Following the hypertrophic scar formation on day 28, intralesional DMSO and triamcinolone acetonide were administered once a week for 4 weeks into these scars of the DMSO and TRA groups, respectively. No therapeutic agent was administered to the control and sham groups. One week after the last injection, ear samples were collected for histopathological, immunohistochemical, and real-time polymerase chain reaction gene expression analyses. Histopathological examination revealed that the epithelium in the DMSO group was thicker than that in the control and TRA groups, but thinner than that in the sham group. Connective tissue thickness and vascularity level of the sham group were higher than those of the control, DMSO, and TRA groups. The collagen type I immunoreactivity level of the sham and TRA groups was higher than those of the control and DMSO groups. The collagen type III immunoreactivity level was higher in the sham group than in all other groups. Collagen type I/type III immunoreactivity ratios were lower in the DMSO group. The alignment of collagen fibers was normal in the DMSO group, but was irregular in the sham and TRA groups. The collagen type I gene expression levels of the DMSO and TRA groups were lower than that of the sham group. Collagen type III and IFN-gamma mRNA expression levels were almost similar among the groups. TGF-1 beta mRNA expression levels were higher in the DMSO and TRA groups than in the control and sham groups. On the basis of the results, it can be concluded that intralesional administration of DMSO decreases hypertrophic scar formation easily and safely. (C) 2017 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.