The aim of this study was to assess physiological demands of competitive basketball by measuring oxygen consumption (VO2) and other variables during practice games. Each of 12 players (20.4 ± 1.1 years) was monitored in a 20-min practice game, which was conducted in the same way as actual games with the presence of referees and coaches. VO2 was measured by a portable system during the game and blood lactate concentration (LA) was measured in brief breaks. Subjects were also videotaped for time-motion analysis. Female and male players demonstrated respective VO2 of 33.4 ± 4.0 and 36.9 ± 2.6 mL/kg/min and LA of 3.2 ± 0.9 and 4.2 ± 1.3 mmol/L in the practice games (P>0.05). They spent 34.1% of play time running and jumping, 56.8% walking, and 9.0% standing. Pre-obtained VO2max was correlated to VO2 during play (r=0.673) and to percent of duration for running and jumping (r=0.935 and 0.962 for females and males, respectively). This study demonstrated a greater oxygen uptake for competitive basketball than that estimated based on a previous compendium. The correlation between aerobic capacity and activity level suggests the potential benefit of aerobic conditioning in basketball.