Objective. - The main aim of this study was to examine the association between the Maximal Aerobic Speed (MAS) measured by the Universite de Montreal Track Test (UM-TT) and on a running treadmill test in young elite soccer players. Equipment and methods.- Fourteen U-16 male soccer players (mean +/- SD: age = 15.5 +/- 0.7 years; height = 1.76 +/- 0.5 m; weight = 67.7 +/- 4.5 kg) from a Spanish First Division club academy participated in the study. The participants were submitted to the Universite de Montreal Track Test (UM-TT) and an intermittent treadmill test with a one-week interval. Results. -The MASs, the speed at the last completed stage (16.6 +/- 0.8 km h(-1)) and calculated using the formula of Kuipers et al. (17.2 +/- 0.7 km h(-1)), were substantially higher (Effect size 0.8) than that measured on the treadmill (15.9 +/- 0.9 km h(-1)). The MAS measured by the UM-TT correlated highly (r > 0.6) with the MAS measured on the treadmill. Conclusion. - Despite the large association between both values, the MAS measured by the UMTT differs considerably from the MAS measured on a running treadmill in young elite soccer players. It suggests that, in soccer training, caution should be applied when using the velocity of the MAS measured on the UM-TT or in a laboratory interchangeably. (C) 2019 Elsevier Masson SAS. All rights reserved.