Prader-Willi syndrome (PWS) is a rare, multifaceted genetic disorder resulting from the absence of normally active paternally expressed genes from the 15q11-q13 chromosome region. Due to a lack of anthropometric and intellectual data in Taiwan, we attempted these evaluations. Twenty patients (14 males/6 females) aged 7-23 years with molecularly confirmed PWS were enrolled with parental consent. Their mean height standard deviation score (SDS) was -1.26 +/- 1.89 (from -4.3 to +2.16); mean weight SDS was +1.77 +/- 2.00 (from -0.44 to +5.89); mean body mass index SDS was +3.84 +/- 10.54 (from -0.08 to +10.48); and mean body fat tissue SDS was 39.4 +/- 10.54% (14.7-57.8%) by an InBody 3.0 analyzer. All were hypogonadal. Nine of them had once been given growth hormone therapy, and were taller and slimmer than the rest. Their intelligence tests showed full intelligence quotient = 52.0 +/- 7.6; verbal intelligence quotient = 55.9 +/- 8.77; performance intelligence quotient = 53.2 +/- 9.0. Chronic health status revealed that diabetes was prevalent among the older population. Their IQ was in the range of those with moderate retardation.