¡¾Abstract¡¿ AIM: To study the value of heart tate variability (HRV) analysis in distinguishing the child ren with STª²T changes in electrocardiogram (ECG). METHODS: In 121 children (40 cases of simple STª²T changes, 40 of viral myocarditis with STª²T changes and 40 normal children), 24 h Holter monitoring were conducted and all HRV parameters (including time domain and frequency domain) were analyzed, and the ECG changes during waking and sleeping periods was observed. With ST depression as dependent variables, all HRV parameters as independent variables ,multiple regression analysis was carried out. RESULTS: In the pure STª²T change group, HRV was increased, HF being 1465¡À197 vs 497¡À201 (P<0.017); the alteration between sleeping and waking periods was more obvious as compared with normal group. In STª²T changes plus viral myocarditis group, HRV was decreased continuously, TP being 2647¡À1328 vs 3121¡À569 (P<0.017), and HF being 305¡À199 vs 667¡À116 (P<0.017); the alteration between sleeping and waking periods was significantly diminished. Multiple regression analysis showed STª²T depression in pure group was correlated with HF/LF, VLF, pNN50N and SDNNN; in myocarditis group, STª²T depression was correlated with VLF, LFN and LF. CONCLUSION: Specific HRV changes were found both in pure STª²T changes and viral myocarditis plus STª²T changes group. There were several useful parameters in distinguishing functional and organic STª²T changes in children. ......