OBJECTIVE: To study the diagnosis of vasovagal syncope (VVS) in children with postural orthostatic tachycardia syndrome (POTS). METHODS: The clinical data of 57 children with POTS diagnosed by the head-up tilt test between January 2007 and December 2010 were studied retrospectively. Of the 57 children, there were 29 boys and 28 girls who were aged from 5 to 16 years (12.2±1.9 years). RESULTS: Twenty-four (42%) out of 57 children were diagnosed with VVS by prolonging the duration of the head-up tilt test (for the children with orthostatic tolerance): cardioinhibitory (20 cases), mixed (3 cases) and vasoinhibitory (1 case). The POTS children with VVS were older than those without (13.0±1.4 years vs 11.5±2.1 years; P<0.05). There were no significant differences in gender and clinical symptoms between the POTS children with and without VVS. CONCLUSIONS: Some children with POTS may have coexisting VVS, suggesting that it is important to avoid misdiagnosis of VVS by prolonging the duration of head-up tilt test in POTS children with orthostatic tolerance. There are no obvious differences in gender and clinical symptoms between the POTS children with and without VVS.