Outer-membrane blebs from two serum-susceptible and two serum-resistant strains of Neisseria gonorrhoeae were characterized. In general, bleb surfaces resembled cell surfaces, but there were qualitative and quantitative protein differences in blebs released by serum-susceptible and serum-resistant strains. Relative to blebs from serum-resistant strains, blebs from serum-susceptible strains expressed reduced amounts of major outer-membrane proteins I and III, and little if any 68,000 Dalton outer-membrane protein.