Background: The aim of this study was to investigate the effect of hydroethanolic Nigella sativa L. extract on skin wound healing in diabetic male rats. Methods This experimental study was conducted on 49 male Wistar rats weighing 220–250 g divided into 7 groups of 7 each: control (nondiabetic untreated), sham (nondiabetic eucerin-treated), nondiabetic phenytoin (1%)-treated, diabetic untreated, and three diabetic groups treated independently with phenytoin 1%, hydroethanolic N. sativa extracts 20% or 40%. Diabetes was induced with 60 mg/kg streptozosin in one administration. After anesthesia, 2 × 1 cm 2 wounds were made on the rats’ backs and each group was administered with its own respective treatment until the wounds were healed completely. Tissue specimens were prepared for histological examinations. The areas of the wounds were measured every 3 days. The data were analyzed by ANOVA and Tukey's post-hoc test. Results: The mean duration of wound healing was 27 and 24 days for diabetic untreated and diabetic phenytoin-treated groups, respectively. Wounds were healed completely in nondiabetic untreated, sham, and nondiabetic phenytoin-treated groups on days 23, 24, and 21, respectively. The shortest duration of wound healing was seen in diabetic N. sativa extract (40%)-treated group (15 days) followed by diabetic N. sativa (20%)-treated group (18 days). These two groups were found to have the lowest mean wound area during the study with a significant difference from mean wound area in the controls ( P < 0.05). Conclusions: N. sativa extract significantly promoted wound healing in diabetic rats in comparison with control groups. Although the beneficial mechanism of the promotion of wound healing was not specifically studied, it is believed that the anti-inflammatory and antimicrobial properties of N. sativa would contribute to this enhanced wound healing.