目的：讨基础直立倾斜试验对不明原因晕厥(UPS)患儿的诊断价值。方法：UPS患儿30例，年龄6～18岁，平均(11.74±2.82)岁，采用电动倾斜床取头高脚低位直立倾斜70° 后每 5 min自动测量血压和心电变化，评价倾斜试验结果。结果：30例UPS中倾斜试验阳性10例(占 33.3%)，反应类型为心脏抑制型及血管抑制型各5例，晕厥发作在倾斜站立10～40 min，平均(24.0±12.2) min。结论：倾斜试验是诊断儿童血管迷走性晕厥(VVS)的有效方法，对临床UPS患儿具有很好地诊断价值。

OBJECTIVE: To study the diagnostic value of head up tilt table test in childhood unexplained syncope. METHODS: Thirty children with this disorder aged from 6 to 18 years old (mean 11.74 ± 2.82 ) were taken the 70 degrees head up tilt table test. Blood pressure and electrocardiogram were recorded at 5 minute intervals by multifunctional monitor in these subjects. The result of the test was evaluated according to the symptoms of patients during the test. RESULTS: Of the 30 subjects, 10 presented positive reaction of head up tilt table test ( 33.3% ), in which 5 showed the reaction type of heart inhibition and 5 of blood vessel inhibition. The syncope episodes occurred after standing time of 10 40 min (mean 24.0 ± 12.2 ). CONCLUSIONS: The head up tilt table test may be a useful method in the diagnosis of vasovagal syncope, helping to determine the origin of unexplained syncope in children