The NF-kappaB family of transcription factors is part of an evolutionarily conserved system that plays an important role in the regulation of genes associated with the development of innate and adaptive responses required for the recognition and immunologic control of pathogens [Clin. Microbiol. Rev. 15 (2002) 414; Annu. Rev. Immunol. 16 (1998) 225; Infect. Immun. 70 (2002) 3311]. In addition, NF-kappaB regulates other cellular processes required for a coordinated immune response, such as cellular growth and differentiation, cell adhesion, survival and apoptosis. Recent studies have highlighted the prominent role played by the NF-kappaB system in resistance to Toxoplasma gondii but it is becoming apparent that this intracellular parasite can directly modulate this signalling pathway. This article briefly reviews the biology of NF-kappaB, examines the complex interaction that takes place between T. gondii and these transcription factors in infected cells, and highlights the role of different NF-kappaB family members during the development of a protective immune response to this pathogen.