The purpose of the present study was to examine the factors affecting adherence to antipsychotic medication in patients with schizophrenia registered with a community psychiatric nursing service in Hong Kong. The study was a cross-sectional observational survey; symptoms, drug attitudes, insight, side-effects, and sociodemographic characteristics were measured and explored in terms of their relationship with medication adherence. A total of 584 patients who were visited by community psychiatric nurses (CPN) participated, and 30% of these patients were non-adherent with their antipsychotic medication. Positive treatment attitudes, awareness of the need for treatment, being prescribed clozapine, receiving state benefits, lower levels of symptoms, and fewer side-effects were associated with adherence. The findings from this study suggest that the clinical efforts of CPN to improve adherence should aim to help patients amplify the personal relevance of treatment and modify patients' attitudes towards medication.