Introduction The usefulness of the seat belt has been widely proven in the world; it avoids the ejection of the passenger and the second impact.

In the state of Sinaloa, Mexico, the prevalence of the seat belt use is 19% and the mortality by traffic incidents is 28 per 100 000 people.

In our incidents studies, we have found that many deaths could have been avoided by the use of seat belt.

Objective To estimate the number of deaths by crash or rollover incidents that were potentially preventable by the use of seat belt.

Material and methods Analysis of the deaths by crash or rollover in the state of Sinaloa in the year 2006.

Classification of the deaths as potentially preventable according to the following criteria: respected vital space in the vehicle cabin (photography material), victim passenger that were not using seat belt, ejected or not ejected, but not pressed, between 12 and 65 years old, not burned, not drowned.

Results In the year 2006, 761 deaths by traffic incidents were registered. 421 of these deaths were by crash or rollover. From these, 153 filled the criteria to be classified as potentially preventable: 73 by ejection and 80 by second impact.

Conclusions 153 deaths (36.3%) were considered potentially preventable with the seat belt use. We recommend to intensify programmes to increase its use and further studies to strengthen the evidence.