To determine the daily energy requirements of soccer players, we measured total energy expen-diture (TEE) in nine Korean Professional Football League players (mean ± SD; age 29 ± 4 years, height 180 ± 7 cm, body mass 75.7 ± 10.3 kg) during 7 days of a competitive season using the doubly labeled water (DLW) method. Energy intake (EI) was simultaneously estimated from 7 days of dietary records. Mean TEE and EI were 16.8 ± 2.4 MJ/day (4,013 ± 583 kcal/day) and 16.4 ± 1.6 MJ/day (3,941 ± 382 kcal/day), respectively. El was highly correlated with TEE (r = 0.747, p<0.05) and was also no significant difference. The physical activity level (PAL = TEE/estimated basal metabolic rate) was 2.22 ± 0.28. We discussed the energy requirements of soccer players during a competitive season based on PAL of both Korean and Japanese Professional Football League players.