Word Count: 2960 words. Abstract 274 words. ABSTRACT ObjectiveMedication arrangements for patients with severe mental illness (SMI), including schizophrenia and bipolar disorder, can be complex. Some have shared care between primary and secondary services whilst others have little specialist input. This study investigated the contribution a specialist mental health clinical pharmacy team could make to medicines optimisation for patients on the SMI register in primary care. Research shows that specialist mental health pharmacists improve care in inpatient settings. However little is known about their potential impact in primary care. MethodFive General Practice (GP) Surgeries were allocated half a day per week of a specialist pharmacist and technician for 12 months. The technician reviewed primary and secondary care records for discrepancies. Records were audited for high dose or multiple antipsychotics, physical health monitoring and adherence. Issues were referred to the pharmacist for review. Surgery staff were encouraged to refer psychotropic medication queries to the team. Interventions were recorded and graded.Results 316/472 patients on the SMI register were prescribed antipsychotics or mood stabilisers. 23 (7%) records were updated with missing clozapine and depot information. Interventions by the pharmacist included clarifying discharge information (12/104), reviewing high dose and multiple antipsychotic prescribing (18/104), correcting errors (10/104), and investigating adherence issues (16/104), following up missing health checks (22/104) and answering queries from surgery staff (23/104). Five out of six interventions possibly preventing hospital admission were for referral of non-adherent patients. ConclusionThe pharmacy team found a variety of issues including incomplete medicines reconciliation, adherence issues, poor communication, drug errors and the need for specialist advice. The expertise of the team enabled timely resolution of issues and bridges were built between primary and secondary care.