The purpose of this manuscript is to define the benefit of exercise test and peak inspiratory flow (PIF) measurement in adult patients with bronchial asthma. Seventy-seven patients--forty-seven from examined group (21 women, 26 men) and thirty patients from control group (8 women, 22 men) participated in this study. Exercise tests (ET) were performed in all subjects in the beginning of the study (ET1) then repeated two months later (ET2) only to the examined group. Patients exercised on a bicycle ergometer for 8-10 minutes to increase the hart rate to submaximal level. Spirometry were performed before and after the study and 5, 10, 15 and 20 minutes later. Symptoms of asthma after exercise and forced expiratory flow in one second (FEV1) decrease more then 15% of predicted value confirmed the diagnosis (positive test result). Thirty patients (74.4%) from examined group had positive results in ET1 and twelve (25.5%)--negative. Four patients (10%) were positive in ET2 and thirty-six (90%)--negative. deltaFEV1 decrease in ET2 was (-14.78%), in ET2 (-4.45%) p < 0.0001. There were twenty-nine (96.6%) negative results in control group, only one (3.4%) positive, p < 0.001. During the study no side effects were observed. The comparison of deltaPIF decrease in ET1 (-11.94%) and ET2 (-7.39%) shows significant difference p < 0.05. PIF decrease was not statistically different between control and study group. Results of the study suggest that exercise tests are safe and easy method of diagnosis and management of asthma. PIF measurement seems to be non-useful in diagnosis of bronchial asthma. It must be confirmed in further studies.