We studied the effect of subinhibitory concentrations of lomefloxacin on bacterial adherence, assessing the presence of fimbriae in E. coli and the adherence to uroepithelial cells of Staphylococcus saprophyticus. The degree of inhibition of fimbriae in E. coli in the log-phase is directly proportional to subminimal inhibiting concentrations (sub-MIC). On the contrary, there is no effect when the bacteria are in a stationary phase. In the case of Staphylococcus saprophyticus the adherence to epithelial cells was observed at concentrations of 1/2 and 1/4 the MIC.