Studies on gonococcal surface components during the past year focused on mechanisms by which these bacterial pathogens alter the structure of their pili and on the affects that lipooligosaccharide (LOS) and opacity-associated (Opa) outer membrane protein constituents exert on gonococcal surface properties. Major recent findings include demonstration that pilin changes that follow transformation with chromo- somal DNA containing pilE (expressed pilin structural gene) fused with a CAT marker result in wholesale replacement of recipient pilE with donor pilE::CAT sequence but little attendant pilin variation. When plasmids with selected pilE::CAT constructions were used for transformation donor DNA, it was clear that 5' and 3' flanking sequence homologies were necessary for complete pilE replacement. If 3' flanking homology was absent, several kinds of change in recipient pilE occurred: micro-recombination tracts, insertion of new hypervariable segments, and deletion between direct repeats of pilE. These data cast serious doubt on the importance of DNA-transformation as a mediator of pilin variation of gonococci. Gonococcal surface properties are being explored in several ways, including use of Doppler electrophoretic light scattering technology to net cell charge. Both LOS and Opa constitution influence cell charge. The charges imparted by members of the repertoire of 10+ Opa proteins expressed by a single strain has been corroborated by examining E. coli that express the analogous but recombinant genes. The negativity imparted by those Opa proteins predicted to have the most opposite (increased positive charge) affects is due to their adsorbing polyanions (DNA, RNA, heparin, sulfated polysaccharides from agar, and perhaps polyphosphate) from their surrounding milieu. When Opa+ cells attain a "polyanion capsule," it greatly reduces their abilities to adhere to epithelial cells in vitro.