The phylum of Apicomplexa groups a large variety of obligate intracellular protozoan parasites that exhibit complicated life cycles, involving transmission and differentiation within and between different hosts. Little is known about the level of regulation and the nature of the factors controlling gene expression throughout their life stages. Unravelling the mechanisms that govern gene regulation is critical for the development of adequate tools to manipulate these parasites and modulate gene expression, in order to study their function in molecular terms in vivo. A comparative analysis of the transcriptional machinery of several apicomplexan genomes and other protozoan parasites has revealed the existence of a primitive eukaryotic transcription apparatus consisting only of a subset of the general transcription factors found in higher eukaryotes. These findings have some direct implications on development of tools.