Heart rate variability (HRV) has been used as prognostic tool in various disorders in pediatric and adult patients. In our study we aimed to evaluate heart rate variability indices and their association with neurological outcome in three children with anoxic brain injury following drowning. Three children included in the study were admitted following drowning and required mechanical ventilation and targeted temperature management. All physiologic data, including electrocardiography (ECG) and EEG were collected for a period of 3-5 days after enrollment. ECG signals were analyzed in both time and frequency domains. The spectral power of the low-frequency (LF) band (0.04-0.15 Hz) and that of the high-frequency (HF) band (0.15-0.4 Hz), the standard deviation of the average R to R ECG intervals (SDANN) were calculated. Mean low-frequency/high-frequency power ratios (LF/HF) were compared using a two-tailed t-test and ANOVA with Tukey-Kramer multiple comparisons. The power in the LF band, the LF/HF power ratio, and the SDANN, were lower in children who had a poor outcome, and during periods of isoelectric or burst suppression EEG patterns.