Background: Low patient satisfaction with the quality of out-of-hours primary care (OOH-PC) has been linked with several individual and organizational factors. However, findings have been ambiguous and may not apply to the Danish out-of-hours (OOH) setting in which general practitioners (GPs) perform the initial telephone triage. This study aimed to identify patient-related, GP-related and organizational factors associated with low patient satisfaction. Methods: The study was based on data from a 1-year population-based survey of OOH-PC (LV-KOS) in the Central Denmark Region in 2010-2011. GPs on OOH duty completed an electronic questionnaire in the OOH computer system, and the registered patients received a subsequent postal questionnaire focusing on contact evaluation, waiting time, demographic characteristics and general self-perceived health. Associations were analysed using multivariable logistic regression with dissatisfaction as the dependent variable. Results: The patient response rate was 50.6%. For all contact types, 82.5% of the patients were satisfied with the OOH-PC service. More patients were dissatisfied with telephone consultations than with clinic consultations or home visits (8.5% vs. 6.0% and 4.3%, respectively). Contacts assessed by the GP as 'not severe' were associated with dissatisfaction for telephone consultations and home visits. Poor general self-perceived health was associated with dissatisfaction for all contact types. Living in urban areas was associated with dissatisfaction for telephone consultations, while unacceptable waiting time was associated with dissatisfaction for all contact types. Conclusions: We found a high level of patient satisfaction with the OOH-PC service. The only factors affecting patient satisfaction across all contact types were unacceptable waiting time and poor general self-perceived health. For the other investigated factors, patient satisfaction depended on the type of contact. Generally, patients contacting for GP-assessed non-severe health problem and patients living in urban areas were more dissatisfied.