A total of 174 sera from healthy Polish individuals of different age groups were tested for TSST-1 antibody by the micro-ELISA method. Over 90% of sera contained the antibody with titres equal to above 1:10(2), even in children and adolescents. The data suggest that the majority of the Polish population acquires TSST-1-antibody during early childhood, whereas a small portion of the population seems to remain anti-TSST-1-negative.