Abstract Background: Risk assessment forms a key component in self-harm management. Among self-harm presentations generally, lethality of an index act is a poor predictor of future non-fatal repetition. However, no study has examined whether severity of an index self-cutting episode is associated with prospective repetition. Aims: To examine factors associated with severity of self-cutting and in particular the association between severity of self-cutting and prospective repetition of self-harm. Methods: All index self-cutting presentations to emergency departments in Ireland over 5 years were grouped by treatment received and compared on the basis of demographic and clinical characteristics. Results: Receiving more extensive medical treatment was associated with male gender, being aged more than 15 years, and not combining self-harm methods. Receiving less extensive treatment conferred a higher risk of prospective 12-month repetition, even after controlling for demographic and clinical characteristics. Repeat self-harm presentations by those with more severe self-cutting in an index act were less prevalent but were more likely to involve high-lethality methods of self-harm. Discussion: The results indicate that the already-elevated repetition risk among self-cutting patients is further increased for those receiving less extensive wound closure treatment. Severity of self-cutting might also affect suicide risk but such an association has yet to be examined.