Data sources Medline/PubMed, Web of Science, Open Grey, Scopus and Cochrane Library databases were searched with no restrictions on dates or language. Study selection Randomised controlled clinical trials (RCTs) comparing the effectiveness of HEMA-free and HEMA-containing adhesive systems in NCCL restorations were included. Data extraction and synthesis Two reviewers extracted data with risk of bias being assessed using the Cochrane tool. The parameters, retention [RE], marginal adaptation [MA], marginal discoloration [MD], caries [CA], postoperative sensitivity [POS] and overall clinical performance were assessed using a random effects meta-analysis. Results Twenty-two studies were included, 13 were at low risk of bias and nine at unclear risk. The number of patients in the studies ranged from 11-124 and study duration ranged from 12 months to 13 years. In all 30 different adhesive systems were tested. For the parameters analysed no significant statistical differences were found between the clinical performances of HEMA-free and HEMA-containing adhesive systems. Conclusions HEMA-free and HEMA-containing adhesive systems showed a similar clinical performance in NCCL restorations.