An analysis of backburning on five fires in northern Manitoba has revealed that the cost of conventional wildfire suppression, or direct attack, can exceed the cost of backburning to secure fireline by a ratio of over 100 to 1. The fires analyzed occurred during the 1995 fire season and all were large fires that had exceeded initial attack capabilities. Due to the severity of the fire season, suppression resources were stretched thin and backburning with a helitorch became a strategy that comprised a major portion of each fire's suppression effort. Documentation of the fires was adequate to permit an analysis of backburning costs for comparison with direct attack. On four of the five fires, it was demonstrated that backburning comprised less than 4% of the total suppression cost while at the same time was responsible for securing an equivalent amount of fireline as direct attack. When related to the cost to secure one kilometre of fireline, backburning costs ranged from $81.00 to $783.00 per kilometre as compared to $20,056.00 to $98,757.00 per kilometre for direct attack. One of the fires in the study was secured using backburning as the only suppression technique. A total of 6.8 kilometres of fireline was secured at a cost of $783.00 per kilometre, a relatively low expenditure when compared to direct attack suppression. The cost effectiveness of backburning can be attributed to three primary factors: (1) a relatively small amount of aircraft, equipment, and personnel are required to conduct a burn operation regardless of its size; (2) a large amount of fireline can be secured in a very short period of time thereby speeding up the suppression effort; and (3) the costs of backburning are a function of time required to complete a burn and do not rise appreciably as the size of a backburn operation or fire increases.