The cell phone when used at the wheel may be a distraction that could be harmful to road safety. A research project on 12 691 drivers users and 23 387 drivers non-users has shown that the users, men as well as women, have relative risks for collisions and for injury collisions that are 38 % higher that for non-users (Laberge-Nadeau et al., 2003). Two questions arise : (i) Are the two cohorts comparable in terms of collision rates before using the cell phone? (ii) How to respond to the argument that cell phones pose no risks since their use is increasing but collision rates diminish? Among the 36 078 respondents of 1999 there were 18 707 with a driver’s permit in 1987 : 5 107 men became users, 7 779 remained non-users, 1 365 and 4 438 respectively for the women. Collision rates in 1987 for the two groups are not significantly different, neither for all collisions, nor for injury collisions. Between 1987 and 1999 the collision rates for non users declined significantly more than for the ones who became users; this result holds for men and for women. In conclusion : (i) On the basis of the collisions in 1987, one can assert that the cohort of male users and the one of female users are comparable, although slightly less safe for the younger users (16-34 years old), to the cohort of male non-users and of female non-users respectively before the use of a cell phone. (ii) The collision rates diminish differently for the two cohorts; they decrease more for the non-users than for the users, both for men and women.