OBJECTIVE: To investigate the effect of pseudoephedrine on heart rhythm of children with rhinitis. METHODS: The study included 25 children diagnosed with rhinitis from March 2009 through February 2010 in the Department of Pediatrics. Holter records were obtained for 24 h before and at the fourth day of pseudoephedrine treatments. RESULTS: Study group consisted of 18 girls (72%) and 7 boys (28%) with a mean age of 8.7 +/- 3.4 (4-17.9 years). Common complaints of the patients were rhinorrhea (100%), cough (68%) fatigue (48%), sore throat (36%), and headache (28%). Of the 25 patients whose Holter recordings were evaluated, rare supraventricular extrasystoles were observed in one prior to the administration of pseudoephedrine, which were not repeated on this patient\'s follow-up recording on day four. There were two ventricular extrasystoles in the day four Holter recording of another patient. None of the patients complained of chest pain or palpitation. There were no observations of supraventricular tachycardia, ventricular tachycardia or ventricular fibrillation. No statistical differences could be found (p > 0.05) in the values before treatment and those on day four of treatment of either the time-dependent Heart rate variability (HRV) parameters SDNN, SDNN index, SDANN and RMSSD, or the frequency-dependent parameters (TP, HF, LF). No statistical difference could be determined between heart rate values of the patients before treatment and those on day four of treatment (p > 0.05). CONCLUSIONS: This study has established that therapeutic doses of pseudoephedrine do not cause an additional dysrhythmia risk for children with no health problem except rhinitis.