High peak inspiratory pressure (PIP) and tidal volume (V(T)) from manual ventilation are hazardous to the neonatal lung. We investigated the influence of operator training on the extent of applied PIP and V(T) between two manual ventilation devices. We performed a prospective, crossover study of 84 medical professionals using a neonatal mannequin. Participants were classified into four groups, according to experience in neonatal resuscitation and previous training in manual ventilation. Provision of PIP, V(T), and inspiratory time (Ti) were compared between groups and equipment used, either a self-inflating bag (SI-bag) or a T-piece resuscitator (Neopuff). Using SI-bags, operator training significantly affected provision of PIP ( P < 0.001), V(T) ( P < 0.001), and Ti ( P = 0.048). Using a T-piece device, PIP and V(T) provision was independent of operator training ( P = 0.55 and P = 0.66, respectively). Twenty-five participants (30%) had previous experience with T-piece devices; this correlated significantly with lower PIP and lower V(T) provision ( P > 0.001 for PIP and V(T)). Operator training level and device-specific experience had a significant impact on PIP and V(T) provision when using SI-bags for manual ventilation. For operators with no specific training in manual ventilation, use of T-piece devices is advised to control for excessive PIP and V(T) application.