Gonococcal entry into primary human urethral epithelial cells (HUEC) fan occur by macropinocytosis. Scanning and transmission electron microscopy revealed lamellipodia surrounding gonococci, and confocal laser scanning microscopy analysis showed organisms colocalized with M-r 70,000 fluorescein isothiocyanate-labeled dextran within the cells. Phosphoinositide 3-kinase inhibitors and an actin polymerization inhibitor prevented macropinocytic entry of gonococci into HUEC.