Donor site wounds of split-thickness skin grafts can be a major cause of morbidity. Choosing the appropriate dressing for these wounds is crucial to successful healing. Various types of dressing are available, including hydrogel dressings. A review of current evidence is required to guide clinical decision-making on the choice of dressing for the treatment of donor sites of split-thickness skin grafts. To assess the effects of hydrogel dressings on donor site wounds following split-thickness skin grafts for wound healing. In July 2022 we searched the Cochrane Wounds Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL EBSCO Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies as well as reviews, meta-analyses, and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication, or study setting. Randomised controlled trials (RCTs) comparing hydrogel dressings with other types of dressing, topical treatments or no dressing, or with different types of hydrogel dressings in managing donor site wounds irrespective of language and publication status. Two review authors independently carried out data extraction, risk of bias assessment using the Cochrane risk of bias tool, RoB 1, and quality assessment according to GRADE methodology. We included two studies (162 participants) in this review. One study with three arms and 101 participants (15 months' duration) was conducted in a children's hospital, and compared hydrogel dressings in the form of Sorbact with Algisite, an alginate dressing and Cuticerin, a smooth acetate gauze impregnated with water-repellent ointment. Another study with two arms and 61 participants (19 months' duration) was conducted in three surgery departments and compared an octenidine-containing hydrogel dressing with an identical non-antimicrobial hydrogel dressing. We identified no studies that compared hydrogel dressings with another therapy such as a topical agent (a topical agent is a cream, an ointment or a solution that is applied directly to the wound), or no dressing, or a combination of hydrogel dressings and another therapy versus another therapy alone. Both studies were at high risk of attrition bias and the second study was also at unclear risk of selection bias. Amorphous hydrogel dressings versus other types of dressings Amorphous hydrogel dressings may increase time to wound healing when compared with alginate (mean difference (MD) 1.67 days, 95% confidence interval (CI) 0.56 to 2.78; 1 study, 69 participants; low-certainty evidence) or Cuticerin dressings (MD 1.67 days, 95% CI 0.55 to 2.79; 1 study, 68 participants; low-certainty evidence). The effect of amorphous hydrogel dressings compared with other types of dressings is uncertain for pain at the donor site and wound complications, including scarring and itching (very low-certainty evidence). No adverse events were reported in any of the groups. The study did not report health-related quality of life or wound infection. Octenidine-based hydrogel dressing versus octenidine-free hydrogel dressing The effect of octenidine-based hydrogel dressings versus octenidine-free hydrogel dressings is uncertain for time to wound healing (MD 0.40, 95% CI 0.28 to 0.52; 1 study, 41 participants) and wound infection, as the certainty of the evidence is very low. The certainty of the evidence is also very low for adverse events, with two participants in the intervention group and one participant in the comparison group reporting adverse events (risk ratio (RR) 0.58, 95% CI 0.06 to 5.89; 1 study, 41 participants). The study did not report donor site pain, health-related quality of life, or wound complications. There is insufficient evidence to determine the effect of hydrogel dressings on donor site wounds of split thickness skin grafts compared with other types of dressings. There is a need for adequately powered and well-designed RCTs, with adequate sample sizes, types of populations and subgroups, types of interventions, and outcomes, that compare hydrogel dressings with other treatment options in the treatment of donor site wounds of split-thickness skin grafts.