AIM(S): To examine Primary Care Trust (PCT) demographics influencing general practitioner (GP) involvement in pharmacovigilance. METHODS: PCT adverse drug reaction (ADR) reports to the Yellow Card scheme between April 2004 and March 2006 were obtained for the UK West Midlands region. Reports were analysed by all drugs, and most commonly reported drugs ('top drugs'). PCT data, adjusted for population size, were aggregated. Prescribing statistics and other characteristics were obtained for each PCT, and associations between these characteristics and ADR reporting rates were examined. RESULTS: During 2004-06, 1175 reports were received from PCTs. Two hundred and eighty (24%) of these reports were for 14 'top drugs'. The mean rate of reporting for PCTs was 213 reports per million population. A total of 153 million items were prescribed during 2004-06, of which 33% were 'top drugs'. Reports for all drugs and 'top drugs' were inversely correlated with the number of prescriptions issued per thousand population (r(s)=-0.413, 95% CI -0.673, -0.062, P <0.05, and r=-0.420, 95% CI -0.678, -0.071, P <0.05, respectively). Reporting was significantly negatively correlated with the percentages of male GPs within a PCT, GPs over 55 years of age, single-handed GPs within a PCT, the average list size of a GP within a PCT, the overall deprivation scores and average QOF total points. ADR reports did not correlate significantly with the proportion of the population over 65 years old. CONCLUSIONS: Some PCT characteristics appear to be associated with low levels of ADR reporting. The association of low prescribing areas with high ADR reporting rates replicates previous findings.