OBJECTIVES: To determine the prevalence, determinants, and potential clinical relevance of adherence with the Dutch dosing guideline in patients with impaired renal function at hospital discharge. DESIGN: Retrospective cohort study between January 2007 and July 2011. SETTING: Academic teaching hospital in the Netherlands. SUBJECTS: Patients with an estimated glomerular filtration rate (eGFR) between 10-50 ml/min/1.73 m(2) at discharge and prescribed one or more medicines of which the dose is renal function dependent. MAIN OUTCOME MEASURES: The prevalence of adherence with the Dutch renal dosing guideline was investigated, and the influence of possible determinants, such as reporting the eGFR and severity of renal impairment (severe: eGFR<30 and moderate: eGFR 30-50 ml/min/1.73 m(2)). Furthermore, the potential clinical relevance of non-adherence was assessed. RESULTS: 1327 patients were included, mean age 67 years, mean eGFR 38 ml/min/1.73 m(2). Adherence with the guideline was present in 53.9% (n=715) of patients. Reporting the eGFR, which was incorporated since April 2009, resulted in more adherence with the guideline: 50.7% vs. 57.0%, RR 1.12 (95% CI 1.02-1.25). Adherence was less in patients with severe renal impairment (46.0%), compared to patients with moderate renal impairment (58.1%, RR 0.79; 95% CI 0.70-0.89). 71.4% of the cases of non-adherence had the potential to cause moderate to severe harm. CONCLUSION: Required dosage adjustments in case of impaired renal function are often not performed at hospital discharge, which may cause harm to the majority of patients. Reporting the eGFR can be a small and simple first step to improve adherence with dosing guidelines.