We have studied the influence of motivation of care providers on the incidence and duration of postoperative hypoxaemia in the recovery room. In a prospective, switch-back designed cohort study, we have compared the incidence of low pulse oximeter saturation values (SpO2) during pre-intervention, intervention and post-intervention phases. Low SpO2 values were classified as either hypoxaemia (SpO2 < or = 90%, minimum duration 1 min) or artefact. Pulse oximetry trend data from 1350 patients, 450 in each group, were analysed. During the intervention phase, motivation was increased by adding an explicit instruction to prevent and treat low SpO2 values and making personnel aware that they were being studied (Hawthorne effect). The incidence of hypoxaemia decreased significantly from 17.8% during the pre-intervention phase to 11.6% during the intervention phase (relative risk (RR) 0.65, 95% confidence interval (CI) 0.47-0.90; P < 0.01). The incidence of severe hypoxaemia (SpO2 < or = 85%, 1 min) decreased from 7.8% to 3.3% (RR 0.43, CI 0.24-0.76; P < 0.01). The number of patients who had severe hypoxaemia for more than 5 min decreased from 13 to 1 (RR 0.08, CI 0.02-0.36; P < 0.01). In the post-intervention period, the incidence of hypoxaemia returned to pre-intervention values. The results of this study suggest that motivation of care providers to prevent and treat low SpO2 is an important determinant of postoperative hypoxaemia in the recovery room.