Background. Over the last years, a system of regional general practices was developed in The Netherlands, responsible for the primary care out-of-hours services (OHS). As in daytime, frequent attendance of the OHS increases workload and the health care; detailed description of the background of frequent attendance is required to develop interventions aiming at reduction. Objectives. To assess the characteristics of the frequent attenders (FAs) and the presented morbidity during their consultations and to study the persistence of frequent attendance. Methods. We performed a retrospective descriptive 1-year database investigation of all patient contacts ( n = 44 953) made in 2007 with the OHS ‘de Gelderse Vallei’. We analysed characteristics of normal attender, FA and very frequent attender (VFA) and compared the reason for encounter, GP diagnoses, psychiatric co-morbidities and management during their 2007 consultations. Results. VFAs, constituting 1% of the attenders and 7.7% of the total number of contacts, more often reported agitation as reason for encounter. The prevalence of psychiatric diagnosis in the VFA group (15.3%) was significantly higher than in other groups. Reassurance was the most frequent prevalent management action in each group. The prevalence of chronic diseases and psychological problems was higher in the VFA groups. Conclusions. Frequent attendance puts severe pressure on OHS resources. Much of the frequent attendance can be explained by the increased incidence of chronic diseases and psychiatric co-morbidity.