The present work concerned the study of the sub-minimal inhibitory doses of tetracyclin, doxycyclin and minocyclin on both hemagglutinating activity and adhesion capacity demonstrated in three E. coli strains isolated from urine. Two different types of hemagglutinins, mannose-resistant (HAMR) and mannose-sensitive (HAMS), were associated in two strains; HAMR was present in the third strain. Adhesion capacity was detected, in vitro, with uroepithelial cells spontaneously eliminated in urine. Whatever the antibiotic used, HAMR titers clearly decreased. In contrast, the effect of these antibiotics on the HAMS titers was inconstant, according to the bacterial strain or the antibiotic used. Adhesion capacity was inhibited particularly in the presence of tetracyclin and doxycyclin. Minocyclin was not a very good inhibitor molecule. The analysis of coefficient of correlation showed that the ability of adhering to uroepithelial cells was related to the HA titers. But it is impossible to say if the same bacterial structure migt be considered as mediator for both HA and adhesion capacity.