High-quality chest compressions (CCs) are the main component of cardiopulmonary resuscitation (CPR). Objectives. T o assess the depth of CCs during CPR using a pediatric patient manikin. A secondary objective was to explore the association between CC depth and sex, level of training, body mass index, and periodic physical training. Prospective study with experimental observation. Pediatric residents, pediatricians, nurses, and other health care providers trained in CPR and who attended children were included. A software program was used to record the depth of CCs while performing CPR during 2 minutes. Tiredness was defined as a deterioration in the number of adequately deep CCs (> 50 mm) by more than 3 CCs between the first and the last cycles. A total of 137 subjects participated (85.4 % were women). Only 48 participants (35.8 %) showed an adequate performance in terms of depth. Significant differences were observed for men (p < 0.0001) and trained pediatricians compared to the rest (p = 0.038). A worsening was observed in performance in terms of depth after 2 minutes in 36.5 % of participants. No significant differences were observed in relation to body mass index and physical activity. Depth rate reduced after 2 minutes. No association was observed with the body mass index or regular physical activity of resuscitators but with their sex and level of training.