Background & aims: An unhealthy diet is a risk factor for ischemic heart disease (IHD) and therefore cardiac rehabilitation (CR) should include dietary interventions. In 2007, CR became a shared responsibility between Danish hospitals and municipalities. Later, a national clinical guideline including recommendations on dietary interventions was developed to facilitate implementation of CR. The aim of the present study is: 1) To describe provision of dietary interventions in CR for IHD patients in Denmark in 2013 and 2015 emphasizing differences between hospitals and municipalities, and 2) To evaluate the implementation of the national clinical guideline in clinical practice. Methods: A repeated nationwide cross-sectional electronic survey was carried out in 2013 and 2015. Participation was mandatory for all Danish hospital departments offering CR (n = 36), but voluntary for municipalities (n = 98) reaching response rates of 82% and 89% in 2013 and 2015, respectively. The electronic survey covered the core components of dietary interventions in CR as described in the national clinical guideline. Results: In 2015, 72% of municipalities provided dietary interventions. This proportion was significantly higher in hospitals (94%, p = 0.007). 26% and 38% of hospitals screened systematically for dietary intervention needs in 2013 and 2015, respectively. Corresponding results from municipalities were 26% and 29%. No significant differences were seen in clinical practice over time. Conclusions: The results of this study identified a major gap between recommendations in the national clinical guideline and actual clinical practice on dietary interventions in CR in Danish hospitals and municipalities. The study confirmed that implementation of guidelines in clinical practice takes time and requires an intensive effort.