Six murine T cell clones expressing γδ TCR were generated from malaria immunized, αβ T celldeficient mice. Phenotypic characterization of these clones has revealed that, in contrast to conventional αβ T cells, there is a considerable degree of heterogeneity among these γδ clones with regard to their surface markers and their lymphokine profile. One clone was found to display significant anti-parasite activity in vivo upon adoptive transfer. We attempted to determine whether the protective clone differs in one or more key characteristics from the non-protective clones. Although no obvious pattern peculiar to the protective γδ clone was observed, it appears that more than one parameter may, in combination, define a distinct protective phenotype, and thus explain the functional difference between the protective and non-protective γδ clones.