Thirty-three tournament-level young Belgian chess players aged 8 to 13 were tested with the French WISC (Wechsler Intelligence Scale for Children). The mean full scale IQ = 121, verbal IQ = 109 and performance IQ = 129. The results suggest that a high level of general intelligence and of spatial ability are necessary to achieve a high standard of play in chess. The high spatial ability of these young chess players suggested by the high performance IQs may go some way towards explaining why males tend to be more numerous than females among high-standard chess players.