A politically initiated national clinical guideline was launched in Denmark in 2013 to improve quality and equality of cardiac rehabilitation (CR) services. The guideline is to be implemented in both hospital and community (municipality) settings due to shared responsibility for provision of CR services. Little is known about implementation outcomes of a guideline in these two settings. We aimed to study this by determining the extent to which Danish CR services in hospitals and municipalities adhered to national recommendations following the launch of the guideline. The study employed an observational, longitudinal design. Data were gathered by a questionnaire survey to compare CR services at baseline, measured in 2013 immediately before the guideline was launched, with CR services at a two-year follow up in 2015. All Danish hospital departments offering CR services (N = 36) and all municipalities (N = 98) were included. Data were analysed using inferential statistics. Hospitals reported improvement of both content and quality of CR services. Municipalities reported no change in content of services, and lower level of fulfilment of one quality aspect. The results suggest that the guideline had different impact in hospitals and municipalities and that the differences in content and quality of services between the two settings increased in the study period, thus contradicting the guideline´s aim of uniform, evidence-based content of CR services across settings.