Interleukin-1 alpha and beta (IL-1 alpha and beta), tumour necrosis factors alpha and beta (TNF alpha and beta) and interferon gamma (IFN gamma) were tested for their chemotactic effects, their effects on chemotactic movement towards N-formyl-methionyl-leucyl-phenylalanine (FMLP) and their effects on random locomotion of human peripheral blood neutrophils through polycarbonate membranes in Boyden-type chambers. Both IL-1 alpha and beta, but no other cytokine tested were chemotactic for neutrophils using 'sparse-pore' polycarbonate membrane. Both TNFs, but no other cytokine, inhibited neutrophil chemotactic movement towards FMLP using the same membrane. No cytokine influenced random migration of neutrophils through polycarbonate membrane of standard pore density. These results suggest that IL-1 may have a role as a chemotactic mediator of inflammation, but that TNFs may inhibit chemotactic migration of neutrophils into inflammatory lesions.