Background GP cooperatives are typically based in emergency primary care centres, and patients are frequently required to travel to be seen. Geography is a key determinant of access, but little is known about the extent of geographical variation in the use of out-of-hours services. Aim To examine the effects of distance and rurality on rates of out-of-hours service use. Design of study Geographical analysis based on routinely collected data on telephone calls in June (n = 14 482) and December (n = 19 747), and area-level data. Setting Out-of-hours provider in Devon, England serving nearly 1 million patients. Method Straight-line distance measured patients' proximity to the primary care centre. At area level, rurality was measured by Office for National Statistics Rural and Urban Classification (2004) for output areas, and deprivation by The Index of Multiple Deprivation (2004). Results Call rates decreased with increasing distance: 172 (95% confidence interval [CI] = 170 to 175) for the first (nearest) distance quintile, 162 (95% CI = 159 to 165) for the second, and 159 (95% CI = 156 to 162) per thousand patients/year for the third quintile. Distance and deprivation predicted call rate. Rates were highest for urban areas and lowest for sparse villages and hamlets. The greatest urban/rural variation was in patients aged 0-4 years. Rates were higher in deprived areas, but the effect of deprivation was more evident in urban than rural areas. Conclusion There is geographical variation in out-of-hours service use. Patients from rural areas have lower call rates, but deprivation appears to be a greater determinant in urban areas. Geographical barriers must be taken into account when planning and delivering services.