Use of visual analogue scales (VAS) can provide reliable assessment of dyspnea. In order to determine if VAS can be used for clinical assessment of asthma we administered the scale to 40 stable asthmatics and found a good correlation (r = -0.72) with the peak expiratory flow rate (PEFR) readings expressed as per cent of predicted normal. The scales were also used to assess severity in 12 acutely ill asthmatics. Values of VAS and PEFR were recorded at the time of admission and twice daily thereafter till discharge from the hospital. The correlation of the two parameters was less than that obtained in stable asthmatics, but graphic parallelism was remarkable.