The study of cardiac rhythm variability (CRV) in bronchial asthma (BA) and its diagnostic significance included 265 patients aged 41.9 +/- 1.36 yr. They were examined using the rhythmocardiographic technique based on the high-resolution diagnostic system KAP-RK-01 "Mikor" (Chelyabinsk) allowing for the evaluation of sinus rhythm wave structure under conditions of targeted stimulation. Statistical and spectral analysis of CRV showed that BA is associated with autonomous dysregulation of pacemaker activity of the sinoatrial node (SAN) in the form of suppressed peripheral vegetative influence on chronotropic function and functional incompetence of SAN pacemaker cells. Non-specific CRV peculiarities of SAN dysregulation inherent in BA were demonstrated, such as decreased general variability due to reduction of the fast sympato-parasympathetic influence and enhancement of humoral and metabolic effects, impaired response to oppositely directed stimuli in the tests with lengthening the time of achievement of maximum reaction and recovery. BA patients showed very low-frequency CRV waves with a period of 35.332 +/- 8,773 s and a spectral power "peak" at 0.021 +/- 0.005 Hz. Their association with bronchial obstruction was confirmed by comparative analysis of CRV before and after intake of a bronchodilator and by correlation of CRV with the results of spirometry and peak flowmetry. The study suggests the possibility to use high-resolution rhythmocardiography in practical work of pulmonologists.