This article presents a systematic review of the frequency of appearance of different causes in highway bus accidents, for which publications have been searched in SCOPUS and WOS databases. This systematic review has been carried out according to the element guidelines. preferred reporting method for systematic reviews and meta-analyses (PRISMA). Factors linked to drivers have been considered and grouped into seven major items. The results show that the most frequent factors in the publications are those referring to company management, followed by factors linked to driving errors. In this way, it is possible to find where to prioritize studies to eliminate the causes of bus accidents on highways