The countermovement jump (CMJ), the V-cut test, the muscle thickness (MT) and the adjacent subcutaneous fat thickness (SFT) of the gastrocnemius medialis (GM) and rectus femoris (RF) are important physiological indicators for success in basketball. The aims of this study were to obtain normative data regarding CMJ and V-cut performance and ultrasound measurements, evaluate between-age-category and between-gender differences in these data and examine the relationships between physical tests and ultrasound measurements. The measurements were recorded in a sample of 131 elite basketball players (66 males) who played in three age-categories (U14, U16, or U18). We performed two-way analysis of covariance tests and age-adjusted partial correlation analyses. U16 and U18 males showed better performance in the CMJ and V-cut tests and lower GM and RF SFT compared to the U14 males ($p \leq .001$) and to age-category equivalent female players ($p \leq .001$). Comparisons between the females did not show significant differences in any of the study variables. V-cut and GMSFT variables explained 53.3% of the variation for the CMJ result in males ($p < .01$). This study reports normative data from CMJ and V-cut tests and ultrasound measurements of different age-category male and female elite youth basketball players. Furthermore, it is the first to show the association and predictive role of subcutaneous fat thickness in physical performance.