The outer membrane protein profiles of four adherent and one reduced-adherence mutant phenotype of Bordetella avium were compared; a non-adherent B. avium-like organism isolated from turkeys was also examined. The organisms were grown on brain-heart infusion agar at 35 C for 36 hours. In addition, one of the adherent phenotypes was grown at 18 C and 40 C. The outer membrane proteins were isolated by sonication and detergent extraction with Triton X-100. Surface characteristics of intact bacteria were examined using negative stain and transmission electron microscopy. The adherent phenotypes had identical protein profiles by electrophoresis. The non-adherent B. avium-like organism lacked at least five of the proteins present on the adherent strains. The non-adherent mutant phenotype had a protein profile similar to that of the adherent organisms, although several proteins were present in much lower concentrations. Fimbriae were found on both adherent and non-adherent organisms. By comparing protein profiles of adherent and non-adherent B. avium we were able to make a preliminary determination of the membrane proteins that lack adhesive properties.