The apical complex is the defining feature of apicomplexan parasites. It provides the major site of secretion of factors necessary for parasite attachment and motility during invasion and egress. It is also one of the seminal structures formed during parasite replication and co-ordinates cell pellicle assembly in daughter cells. Despite thorough characterisation of the ultrastructure of the apical complex in several apicomplexan taxa, very few proteins have been identified that are specific to this structure, and thus its functional dissection has been limited. We have identified novel proteins located in apical complex structures from a broader study of structural proteins of pellicles in alveolates (apicomplexans, ciliates and dinoflagellates). In Toxoplasma gondii we have localised one protein, called RNG2, to the apical ring that sits at the top of the subpellicular microtubules and the base of the conoid. The RNG2 ring appears as one of the earliest structures of the daughter cell pellicle, forming immediately after centrosome duplication. We have generated an inducible mutant of RNG2 in T. gondii, and demonstrate that knockdown of RNG2 expression severely impairs parasite growth. We show that parasite replication rate is not affected once parasites are established within the host cell, despite the early presence of RNG2 in daughter cells. Invasion efficiency, on the other hand, is substantially reduced, and secretion of both micronemes and rhoptries is retarded. Our data, for the first time, implicates the apical ring in parasite invasion.