Background In 2010, a database of drug related problems (DRPs) was implemented to assist clinical pharmacy staff in documenting clinical pharmacy activities locally. A study of quality, reliability and generalisability showed that national analyses of the data could be conducted. Analyses at the national level may help identify and prevent DRPs by performing national interventions. Objective The aim of the study was to explore the DRP characteristics as documented by clinical pharmacy staff at hospital pharmacies in the Danish DRP-database during a 3-year period. Setting Danish hospital pharmacies. Method Data documented in the DRP-database during the initial 3 years after implementation were analyzed retrospectively. The DRP-database contains DRPs reported at hospitals by clinical pharmacy staff. The analyses focused on DRP categories, implementation rates and drugs associated with the DRPs. Main outcome measure Characteristics of DRPs. Results In total, 72,044 DRPs were documented in the DRP-database during the first 3 years of implementation, and the number of documented DRPs increased every year. An overall stable implementation rate of approximately 58 % was identified. The DRPs identified were multi-facetted, however evenly distributed for each of the 3 years. The most frequently identified DRP categories were: "Dose", followed by "Nonadherence to guidelines" and "Supplement to treatment". The highest implementation rates were found for the following DRP categories: "Non-adherence to guidelines" (79 %) followed by "Therapeutic duplication" (73 %) and "Dosing time and interval" (70 %). Even though the top 25 drugs were involved in 58 % of all DRPs, multiple drugs were associated with DRPs. The drugs most frequently involved in DRPs were paracetamol (4.6 % of all DRPs), simvastatin (3.0 %), lansoprazole (2.7 %), morphine (2.6 %) and alendronic acid (2.4 %). Conclusions The study found that a national database on DRPs contained multi-facetted DRPs, however evenly distributed for each of the 3 years. Even though the top 25 drugs were involved in 58 % of all DRPs, multiple drugs were associated with DRPs. The study emphasizes the importance of detecting and intervening for DRPs.