The study describes the epidemiology and characteristics of unintentional carbon monoxide (CO) poisoning in Northwest Iran between 2007 and 2009 using multiple data sources including records of the main provider of emergency medical transportation, death certificate reports of the Legal Medicine Organization and through household surveys. A total of 1005 people were diagnosed with non-fatal CO poisoning. Ninety deaths were confirmed due to CO exposure. The ratio of unintentional CO-related poisoning cases in relation to all poisonings was 17.6%. Non-fatal CO poisoning was higher in females and adults aged 25-44 year olds, whereas the death rate was highest for those over 64 years. Domestic gas appliances were involved in 98% of non-fatal incidents and in all fatal poisonings, with gas water heaters (59.2%) and free-standing heaters (25.3%) being the most common causes of CO exposure. The main mechanisms of poisoning were faulty installations and defective devices. The main locations of incidents were the bathroom (48%) and living room (32%). Only 19% of the households reported that they were aware of the hazards of CO exposure before the incident, and no household reported having a CO detector at the time of the poisoning. The results suggest that interventions should be targeted at home environments and focus on at-risk groups such as women and elderly people. Setting stricter standards and environmental legislations and promotion of public awareness against the dangers of CO exposure are important considerations for overcoming this public health problem.