Hydroxymethylglutaryl-CoA reductase inhibitors (statins) are drugs used in the treatment of chronic diseases and frequently in concomitant therapy with many other drugs. Therefore, the risk of adverse drug reactions (ADRs), especially those caused by interactions is high. Aim of the study was to describe and analyze ADRs caused by statins reported to Croatian Agency from March 2005 to December 2008, and to emphasize reasons of their occurrence. 136 of statin ADRs were reported. 12 % of all reported statins' ADRs were caused by interactions, which is higher than percent (5.6%) of interactions caused by all other drugs in 2005 and 2006. Proportion of serious ADRs related to administered dose and thus preventable was higher than proportion of all ADRs caused by statins (p = 0.003). Most serious ADRs could have been prevented with better understanding of interactions and by use of pharmacogenomics in identifying patients that are because of genetic predisposition more sensitive to standard doses.