Patients with first episode mania have high risk of treatment and medication non-adherence, which impacts adversely on illness course. Understanding what factors relate to non-adherence is essential for improving clinical care and management as well as outcomes. The aim of this study was to examine treatment and medication adherence in 74 patients (n=50 males) with first episode mania aged between 15 and 29 years. These patients were recruited to a randomised controlled trial investigating the efficacy of combination treatment with lithium and olanzapine versus lithium and chlorpromazine. Patients were being treated at the Early Psychosis Prevention and Intervention Centre, Melbourne Australia. Treatment adherence and serum lithium levels were assessed on a weekly basis over an eight week period. Data on symptoms and functioning was collected at baseline, and weeks 1, 2, 3, 4, 6 and 8. Patients were categorised into two groups based on treatment adherence and serum lithium levels: 1) adherers and 2) non-adherers. Differences between these two groups in terms of symptoms and functioning will be examined using mixed models repeated measures analysis of variance. A model of non-adherence in first episode mania will be described and suggestions will be made regarding clinical implications.