Abstract. Background: The rise in Internet use adds a new dimension to suicide prevention. We investigated suicide/self-harm (S/Sh)-related Internet use among patients presenting to hospital with self-harm. Method: We asked 1,198 adult and 315 child and adolescent patients presenting to hospital following self-harm in a city in South West England about Internet use associated with their hospital presentation. Associations between Internet use and sociodemographic and clinical characteristics were investigated using multivariable logistic regression models. Focus groups with clinicians explored the acceptability and utility of asking about Internet use. Results: The prevalence of S/Sh-related Internet use was 8.4% (95% CI: 6.8–10.1%) among adult hospital presentations and 26.0% (95% CI = 21.3–31.2%) among children's hospital presentations. In both samples, S/Sh-related Internet use was associated with higher levels of suicidal intent. Mostly, clinicians found it acceptable to ask about Internet use during psychosocial assessments and believed this could inform perceptions of risk and decision-making. Limitations: It is unclear whether the findings in this study are applicable to the general self-harm patient population because only those who had psychosocial assessments were included. Conclusion: S/Sh-related Internet use is likely to become increasingly relevant as the Internet-native generation matures. Furthermore, Internet use may be a proxy marker for intent.