The objective of this study was to assess the effectiveness of bag-valve-mask ventilation performed by emergency medical technicians with prehospital clinical responsibilities and to compare this with anaesthetists working clinically in tertiary referral teaching hospitals. Participants were asked to perform bag-valve-mask ventilation for three minutes on a Resusi Anne manniquin using a facemask and a two litre self inflating bag. The tidal volumes generated were quantified using a Laerdal skillmeter computer as grades 0-5 corresponding to 0, 335, 434, 561, 673 and > 800 mls. The effectiveness of bag-valve-mask (i.e. the proportion of ventilation attempts which achieved a tidal volume of > 434 mls) was greater for emergency medical technicians [88.2 (17.1)%] than for anaesthetists [40.4 (36.5)%] (P<0.001). Six of the 27 anaesthetists, but none of the 29 emergency medical technicians, were unable to produce even one effective tidal volume i.e. > 434 mls. It is likely that emergency medical technicians are able to perform adequate bag-valve-mask ventilation.