The objective in this study was to calculate costs and benefits caused by a safe community injury prevention programme in Motala, Sweden. The study design was a quasi-experimental evaluation involving an intervention population and a non-random control population. All injuries were recorded before and after an intervention programme. The presented calculations show that costs of injuries in a societal perspective decreased from 116 million Swedish Crowns (SEK) to 96 million SEK, while the cost for the intervention was estimated at approximately 10 million SEK. Thus, the safe community injury prevention programme in Motala should be judged as cost-effective.