The term 'concussion' has been applied to head injuries of varying sev
erity. Most studies have examined subjects suffering concussion of a s
everity requiring hospital observation, usually as a consequence of mo
tor vehicle accidents. Milder concussive injuries such as those result
ing from contact sport are often not reported in hospital-based studie
s. In this study, subjects with mild concussive injuries were studied
with the aim of determining ifneuropsychological sequelae are detectab
le. The subjects received their injuries while playing Australian Rule
s Football. Baseline (pre-injury) measures on the Paced Auditory Seria
l Addition Test (PASAT), Digit Symbol Substitution Test (DSST) and Fou
r-Choice Reaction time, involving measures of decision time (DT) and m
ovement time (MT), were obtained in a sample of 130 players. Ten playe
rs subsequently concussed were re-tested at 5 days post-injury. A cont
rol group of age-matched umpires were assessed on two corresponding oc
casions. Analyses of covariance showed poorer performances following c
oncussion on the DSST and DT measures. The results suggested that neur
opsychological deficits are detectable after resolution of neurologica
l symptoms in the early stages following mild concussive injury.