Background: Literature shows that patients with obesity and Obstructive Sleep Apnea (OSA), both occurring independently, are more likely to develop cardiovascular diseases and sudden cardiac death (SCD). Assuming that ventricular depolarization is more stable than repolarization then QT interval parameters may be used for heart muscle repolarization assessment for those groups of patients. Methods: There were 121 patients included in the study, both - women and men, aging from 35-65 with visceral obesity. Only healthy patients were included - the ones who were not treated for any chronic disease, taking QT elongating drugs, or were not treated with Continuous Positive Airway Pressure (CPAP) therapy at that time. Results: OSA was diagnosed in 70 patients (including 41 males). A statistically significant difference for QT interval parameters between OSA positive and negative patients was found (p<0.001 for all variables). No difference for QTc max or for QT interval parameters between groups of patients with different OSA severity degrees was found. A correlation between QTVi2 and QTVi3 (p=0.008) and between polygraphy specific parameters and QTc max, QTVi2 and QTVi3 was found. Conclusions: OSA has a negative influence on heart muscle repolarization processes by increasing QTV and QTVi values, without such an impact on QTc max interval among patients with visceral obesity. A temporary intensification of OSA causes an additional increase in QTVi value. OSA severity degree expressed by specific parameters taken from polygraphic examination prolongs QTc max and increases QTV and QTVi values.