text: Altered cardiac autonomic function after recovery from COVID 19 Autonomic dysfunction may occur during the acute phase of COVID 19 Heart rate variability HRV is a useful tool for the assessment of cardiac sympathetic and parasympathetic balance We aimed to evaluate cardiac autonomic function by using HRV in subjects after recovery from COVID 19 who had previously symptomatic and were followed outpatiently The study group composed of 50 subjects with a confirmed history of COVID 19 and the control group composed of 50 healthy subjects without a history of COVID 19 and vaccination All the study participants underwent 2 dimensional pulsed and tissue Doppler echocardiographic examinations and 24 hour Holter monitoring for HRV analysis Time domain parameters of SDNN SDANN SDNNi RMSSD pNN50 and HRV triangular index were all decreased in the study group when compared with the control group Frequency domain parameters of TP VLF LF HF and HFnu were also decreased in the study group in comparison with the control group LFnu was similar between groups Nonlinear parameters of HRV including α sub 1 sub and α sub 2 sub decreased in the study group By contrast Lmax Lmean DET REC and Shannon entropy increased in the study population Approximate and sample entropies also enhanced in the study group The present study showed that all three domain HRV significantly altered in patients after recovery from COVID 19 indicating some degree of dysfunction in cardiac autonomic nervous system HRV may be a useful tool for the detection of preclinical autonomic dysfunction in this group of patients 