Quantifying body composition (BC) has played an important role in monitoring athlete’s health and performance. Skinfolds (SK) is the most commonly used method, however, it is an indirect method, whereas ultrasound (US) measures subcutaneous adipose tissue (SAT) directly with high accuracy and precision. PURPOSE: Estimation of the inter- and intra-tester reliability of the US method for assessment of BC in athletes, compared with the widely used SF method. METHODS: 3 male and 3 female athletes (mean±SD: age: 24±1.7 yrs, weight: 61.5±6.7 kg, height: 1.73±0.8 m, BMI: 20.6±1.5 kg/m2) with competitive background in endurance sports were measured by three trained anthropometrists. SF were taken according to ISAK standardization at biceps, triceps, subscapular, suprailiac, supraspinale, abdomen, front thigh, and medial calf. For US measurements, some ISAK sites were replaced by sites which are better suited for the US technique: biceps, distal triceps, supraspinale, upper abdomen, lower abdomen, erector spinae, front thigh, and medial calf. For US image evaluation, the FAT software (Rotosport, Graz, Austria) was used. Inter- and intra-tester variations were calculated using pooled estimates. For intra-individual variation, a pooled standard diviation (SD) was computed for the six subjects per observer per site. For inter-individual variation, a SD was calculated for the six subjects by site combining all three observers’ data. RESULTS: At equivalent sites, US had lower SD at four sites compared with SF method. For US analysis, intra-tester reliability ranged from 0.03-0.79mm SD. For inter-tester values, US showed values ranging from 0.42-0.62mm SD (with exception of 0.70mm for the upper abdomen and 1.51mm for lower abdomen), while SF resulted in values ranging from 0.38-1.09mm SD. The larger values resulting in the abdominal area using US may be due to embedded structures within the region. CONCLUSION: The US method showed good reliability when compared with SF (one exception was abdomen which showed less reliability). US measures uncompressed SAT, whereas SF measures two layers of skin and SAT, both tissues with undefined thickness reduction due to compression.