The selection of effective maximal expiratory was evaluated using discriminant analysis of asthmatic patients and healthy adults in this review. Maximal expiratory volume-time and flow-volume (MEVT and MEFV) curves were drawn for young non-smoking healthy subjects and for young male non-smoking asthmatic patients. Eleven indices, two MEVT (%FVC and FEV(1.0%)), six MEFV (PEFR, Flow(75), Flow(50), Flow(25), Flow(10) and Flow(50)/Flow(25)) and three mean time constant (MTC) indices (MTC(75-50), MTC(50-25) and MTC(25-RV)) were used for the discriminant analysis using an all possible selection procedure (APSP). In the eleven-indices discriminant analysis using a single index, Flow(75), Flow(50) and Flow(25) were effective indices. In the discriminant analysis through APSP, PEFR, Flow(75), MTC(75-50) and FEV(1.0%), which were at high lung volumes, were the set of the most effective four indices. These four indices appear to be effective in assessing bronchial asthma through a visual evaluation of MEFV curves. Therefore, discriminant analysis is appropriate in assessing the MEFV curves.