Pulsatile electromagnetotherapy (PETh) stimulates biological tissues and processes; it modulates ion exchange across cell membranes and thus regulates the tone of smooth muscles. On the basis of these effects we hypothetized that PETh might treat COPD and bronchial asthma. We examined 117 (61 females, 56 males) adult patients who were decided in 4 groups. The 1st consisted of 16 patients with COPD who were treated by PETh and pharmacologically. The 2nd group (control) consisted of 24 patients with COPD who were treated only with medicaments. The 3rd group consisted of 37 asthmatics, treated by PETh and medicaments. The 4th group (control) consisted of 40 asthmatics treated only with medicaments. The effectiveness of PETh was assessed by lung function tests, which were performed using a Spirometer 100 Handi (Germany). We measured FVCex, FEV1, percentage of FEV1/FVCex, MEF25, 50, 75, PEF and registered the flow-volume loops. PETh was applied by apparatus MTU 500H (Therapy System, Czech Republic). It was administered 10 doses; once daily for 20 min, with a frequency of 4.5 Hz and a magnetic induction 3 T. The initial 3 doses were about 25% lower then the later doses. PETh was very effective in patients with COPD. The measured indexes improved about 200-660 ml or ml x s(-1), except FVC. PETh was less effective in asthmatics. Most indices improved without statistical significance, about 50-620 ml or ml x s(-1). The indices of FEV1/FVC and MEF25 deteriorated. The changes in controls without PETh were very small. (Tab. 2, Fig. 1, Ref. 19.)