Aim of the study: was to estimate an influence of acute cellular rejection on electrophysiologic parameters of allograft and remnants of recipient’s heart, in patients after orthotopic heart transplantation (OHT). Patients and methods: Analysis was performed in 25 OHT recipients (24M/1F, age 48.4±9y., ischemic time 197±51min., donor age 30±9y.), who underwent electrophysiological study (EPS), along with elective endomyocardial biopsy (EMB), scheduled for the 1st month after the surgery. Results of EPS were correlated with a degree of rejection, assessed with the ISHLT grading system. Grades ≥3A were considered a significant cellular rejection. Results: ISHLT grade 0 was observed in 8 patients, grade 1A or 1B in 12 patients, and 3A in 5 patients. Frequency of transplanted heart rhythm (TH-R) was 691.3±37ms in patients with ISHLT grade 0, 690.4±41ms in patients with grade 1A or 1B, and 744.4±668ms in individuals with 3A rejection (p< 0.04, for difference between 0 and 3A groups). Intraatrial conduction time (IntrtaCT) was significantly shorter in grade 3A group (20.4±1.6ms), when compared with patients without rejection (36.2±4.9ms, p

Keywords: Heart Transplantation, Acute Cellular Rejection, Electrophysiological Parameters