Young convalescents after oncological treatment are at risk of toxic cardiomyopathy development. An evaluation of their capability to an exercise or sport needs examination of heart state. Goal of work: To evaluate the heart rate variability (HRV) analysis as a screening method in early diagnostics of toxic cardiomyopathy by patients after oncological chemotherapy in childhood. The study was designed as an individual correlation test of HRV parameters to echocardiographical values. Probands: 85 girls and boys after oncological treatment by doxorubicin and/or cyclophosphamid; aging 7-29 years. Heart rate (beat to beat) was monitored during 5 minutes of vertical position, and in upright position. The echocardiographical measurement was performed in a rest and after dynamic exercise. The values of the HRV parameters have no normal distribution. We found close relations of the rest ejection fraction to 3 HRV parameters – to spectral power of HF band in lying position, and to MSSD in lying and in stand-up position. Both of last HRV parameters represent above all a vagal activity. We found a close relation of after-stress ejection fraction to only one HRV parameter – to VLF/LF spectral power rate in lying position. Close relations were found in difference of the rest – after-stress EF (d-EF) to seven HRV parameters in lying position. Therefore we believe that HRV analysis, as an instrumental, timing and personal less demanding method, can be used for cardiomyopathy screening in oncological paediatric patients before exercise and sport practise.