A population of young adults, 92 men and 107 women, with a mean age of 21 (+/- 0.7) years, were retrospectively questioned about their habitual physical activity levels (period of 3 months) and the incidence and duration of upper respiratory tract infection (URI) symptoms (period of 6 months). We hypothesized that the incidence and duration of URI symptoms were inversely related with the level of sports activity and total physical activity. Only in women was a statistically significant (P less than 0.05) negative relation found between the incidence of URI symptoms and the level of sports activity. However, the low Spearman's rho coefficient (-0.18) indicates a very weak relation between both parameters.