We aimed to study whether three forced expiratory blows are really necessary at each time point following the bronchoprovocative challenge and whether the first or second forced expiratory maneuver gives the highest FEV1 value > 90% of the time. We conducted a study in 12 subjects who underwent two bronchoprovocation tests on separate days at least a week apart with AMP and determined how frequently the best FEV1 value was obtained during the first, second, and third forced expiratory maneuvers after sufficient motivation to give their best effort at each of the three blows. These were recorded as best, second best, and third best (highest to lowest FEV1 values), and their corresponding blow numbers were recorded (first blow, second blow, and third blow). The first blow produced the best FEV1 in 43.49% of the times, while the second and third blows produced the best FEV1 values 24.59% and 31.92% of the times, respectively. Using only one blow (as suggested by Cockcroft and colleagues) would have missed the best FEV1 value 56.51% of the times, while using two FEV1 blows would have missed the best FEV1 31.92% of the times. We therefore conclude that in order to obtain reliable FEV1 values during bronchoprovocation testing, at least three forced expiratory blows are required at each time point. Asking the subject to perform only one forced expiratory blow would give unreliable FEV1 values, which would likely give false PD20 values.