Mobile phones (MP) are widely used especially by young people. It is possible that electromagnetic field (EMF) generated by MP may have an influence on the autonomic nervous system (ANS) and hence the heart rate variability (HRV). The aim of the study was to estimate the influence of the call with a mobile phone on HRV in young healthy people. The time and frequency domain analysis of HRV were performed to assess the changes in sympathovagal balance in a group of 25 healthy students with normal electrocardiogram (ECG) at rest. The frequency domain variables were computed using PowerLab® acquisition system: very low frequency (VLF) power, low frequency (LF) power, high frequency (HF) power and LF/HF ratio was determined. ECG was recorded in standardized conditions: from 09:00 to 11:00 in the morning in a sitting position, within 15 min periods: before the telephone call (period I), during the call with use of mobile phone (period II), and after the telephone call (period III). Mean heart rate did not change significantly over 15 min period before the telephone call (period I), during 15 min telephone call (period II) and after the telephone call (period III) (respectively 96.62 ± 1.10; 126.80 ± 2.63; 106.21 ± 3.32). The analysis of the time domain HRV parameters for the period I, II and III showed that SDNN (Standard Deviation of Normal to Normal intervals) was significantly higher during the telephone call (period II, 214.72 ± 1.12) in comparison with period I (195.49 ± 2.94) and period III (194.98 ± 4.77). The rest of the parameters of the time analysis did not differ significantly from each other. Frequency domain demonstrated that VLF, and HF parameters were significantly increased over the 15 minute period of the telephone call in comparison with the 15 min period before it. While LF was significantly decreased during 15 min period after the telephone calls in comparison with the time of the telephone call. LF/HF ratio was also significantly lower during the telephone call in comparison with the period before and after the telephone call. The increases in the parasympathetic tone concomitant with the decrease in the sympathetic tone, measured indirectly by analysis of heart rate variability, were observed during the mobile telephone call. HRV analysis may be used as a tool to monitor the effects of mobile phones on the cardiovascular system. Changes in heart rate variability during the call with a mobile phone could be affected by electromagnetic field, but the influence of speaking cannot be excluded.