Patient safety is an essential factor in health care. Globally and in Finland medication incidents are usually the most common types of errors that are a threat to the safety of the patients. The purpose of this bachelor’s thesis was to analyze the types of reported medica-tion incidents in service housing units in Vaasa during the first half of the year in 2012. The thesis also aimed to study what the contributing factors were to the oc-currence of these incidents and what type of actions should be taken to prevent these incidents from happening again. The material consisted of 57 reported incidents and was collected from the HaiPro incident report system. The analysis of the reports was done by using both qualitative and quantitative research methods. The results showed that according to the HaiPro reports the most common type of incident was a failure to administer medication and more specifically it’s subcategory of omission of medication. The second most common type of incident was administration of medication to the wrong patient. The qualitative findings showed that according to the reporters the most common contributing factors to the occurrence of the incidents were general negligence and carelessness and that the residents were left to take the medication unsupervised. Other common factors were hurry, the lack of personnel and nurses that had just started working in the units or were substitutes and weren’t aware of all the practices of the work place. The most common suggestions to prevent incidents from being repeated were to talk about them in meetings or to plan a corrective measure. The study showed that more attention should be paid into the processes related to the administration of medication and how to prevent the omission of medication. In the future it would be useful to further research the medication incidents in service housing units because not many studies have been made previously, especially not in Finland.