Secondary school teachers are one of the occupational groups presenting the highest levels of sick leave due to stress in the workplace. This form of stress can cause burnout syndrome, which is characterised by emotional exhaustion, depersonalisation and low levels of personal accomplishment. Secondary education teachers have received relatively little research attention in this respect. This study addresses the prevalence among secondary school teachers of burnout syndrome, in its three dimensions, and investigates possible differences in the prevalence determined by different measuring instruments. A systematic review and meta-analysis was conducted of the scientific literature in this field. Using the Proquest and Eric electronic databases, 45 articles and 49 independent samples (N = 14,410) were obtained. Results show that secondary school teachers are at high risk of burnout syndrome. Moreover, there are statistically significant differences between the different measuring instruments used. Pedagogical programmes should be developed to reduce/prevent its impact.