Traffic-related accident is one of the important issues which threaten public health. The problem is becoming more sophisticated in Iran and there are lots of young victims due to car accidents. In order to find out the effective factors in traffic accidents, regression models such as logistic models (LR), and CRT can be used.This article investigates the reasons of road traffic accident reduction when benefitting from GLM, CRT, LR regression models. The main three factors involved in accidents were known to be human, road, and car - related factors. Statistical samples were 343, 082 cases of Iran roads accidents during the year of 2007.