The fluctuating course of tidal volume (VT), breathing frequency (DF) and minute ventilation (VE) during the cardio-pulmonary exercise test using a ramp incremental protocol occurs not only in patients, but relatively frequently also in healthy individuals. It can account for a number of irregularities in the course of the curves VO2, VCO2 and in particular of those of ventilatory equivalents for O2 and CO2 (EQO2, EQCO2) as well as curves of partial pressure of end-tidal oxygen and partial pressure of end-tidal carbon dioxide (PETO2, PETCO2), which are also used, inter alia, to establish ventilatory thresholds. The presence of exercise oscillatory ventilation (EOV) reflects the severity of heart failure and it is an independent predictor of the increased morbidity, cardiac and total mortality and sudden death caused by heart failure. However there is not a generally accepted universal definition of EOV available at present, as different criteria are used. We have not found a comparison which would indicate whether and how the "strength" of the prognostic criteria for EOV - established according to different methods - differs. Therefore it is very important to specify what method, or what criteria were used in the establishment of EOV.Key words: breathing pattern - EOV - exercise oscillatory ventilation - periodic breathing.