A number of mouth-to-mask ventilation devices have become commercially available in the past several years. In this study, we compared the volumes delivered by eight of these devices to the volumes delivered by mouth-to-mouth ventilation. METHOD: Fourteen respiratory care practitioners participated in the study. Ventilation was delivered to an adult resuscitation manikin. Each subject ventilated the manikin using mouth-to-mouth technique and each of the following mouth- to-mask devices: Boehringer EVA, Hospitak, Hudson, Intertech Safe Response, Laerdal Pocket Mask, Life Design Systems (LDS), Respironics SealEasy, and Vital Signs. Evaluation periods of 1 minute were used, minute ventilation and respiratory rate were measured, and tidal volume was calculated. RESULTS: There was a significant difference between the volumes delivered by the masks (p < 0.001). The volumes delivered by each mask were less than mouth-to-mouth volumes (p < 0.05 in each case). The mean ± SD mouth-to-mouth volume was 1.04 ± 0.32 L. The mean ± SD volumes for each of the devices was 0.54 ± 0.34 L for the EVA, 0.77 ± 0.21 L for the Hospitak, 0.51 ± 0.26 L for the Hudson, 0.81 ± 0.35 L for the Safe Response, 0.65 ± 0.25 L for the Pocket Mask, 0.82 ± 0.27 L for the LDS, 0.79 ± 0.32 L for the SealEasy, and 0.76 ± 0.21 L for the Vital Signs. CONCLUSIONS: We found considerable variability between the volumes delivered with commercially available mouth-to-mask ventilation devices. Although the volumes delivered during mouth-to-mask technique were less than those delivered with mouth-to-mouth technique, the volumes delivered by some of the mouth-to-mask devices were large enough to allow them to be substituted for mouth-to-mouth technique.