To study the diagnosis of vasovagal syncope (VVS) in children with postural orthostatic tachycardia syndrome (POTS).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).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.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.