Purpose: This meta-analysis aims to verify the efficacy of occupational health and safety (OHS) training in terms of knowledge, attitude and beliefs, behavior and health. Design/methodology/approach: The authors included studies published in English (2007-2014) selected from ten databases. Eligibility criteria were studies concerned with the effectiveness of OHS training for primary prevention of workplace injury; and studies focused on examined outcome related to OHS. Findings: The selected studies (n = 28) highlighted a strong support for the effectiveness of training on worker OHS attitudes and beliefs and, to a lesser extent, on worker's knowledge but only medium for behavior and small evidences for its effectiveness on health. Research limitations/implications: Future research should more deeply investigate the efficacy on knowledge increase of trainings delivered by experts and researchers, applying different methods, in a small group; training delivered by peer and by researcher, applying different methods; and trained workers less than 29 years and more than 49 years old, considering that workers in these age groups are particularly vulnerable to fatalities. Practical implications: Our study is a contribution for those they intend to grant effective training, in response to specific needs of OHS. The evidences presented could be considered a first step to identify the factors related to the efficacy of OHS training to plan adequate interventions. Social implications: The OHS training is effective on the basis of the extent interventions are carried out for each specific learning outcome. Originality/value: This meta-analysis suggested that classroom training, although the most used and studied, does not ever reveal itself very effective--it was not significant for outcomes in terms of knowledge and showed a decreasing efficacy for attitudes and beliefs, behaviors and health. It seemed that there was a distinction between interventions on knowledge, attitudes and beliefs, as opposed to behavioral interventions and health.