The role of flagella and motility inthe attachment of the foodborne pathogen Listeria monocytogenes to various surfaces is mixed with some systemsrequiring flagella for an interaction and others needing only motility forcells to get to the surface. In nature this bacterium is a saprophyte andcontaminated produce is an avenue for infection. Previous studies havedocumented the ability of this organism to attach to and colonize plant tissue.Motility mutants were generated in three wild type strains of L. monocytogenes by deleting either FlaA, the gene encoding flagellin,or motAB, genes encoding part of the flagellar motor, and tested for both theability to colonize sprouts and for the fitness of that colonization. The motAB mutants were not affected in the colonization ofalfalfa, radish, and broccoli sprouts; however, some of the FlaA mutants showed reduced colonization ability. The bestcolonizing wild type strain was reduced in colonization on all three sprouttypes as a result of a FlaA deletion. A mutant in anotherbackground was only affected on alfalfa. The third, a poor alfalfa colonizerwas not affected in colonization ability by any of the deletions. Fitness ofcolonization was measured in experiments of competition between mixtures ofmutant and parent strains on sprouts. Here the FlaAand motAB mutants of the three strainbackgrounds were impaired in fitness of colonization of alfalfa and radishsprouts, and one strain background showed reduced fitness of both mutant typeson broccoli sprouts. Together these data indicate a role for flagella for somestrains to physically colonize some plants, while the fitness of thatcolonization is positively affected by motility in almost all cases.