Rhoptries are apical organelles which play an important role in erythrocytic invasion. A Plasmodium falciparum cDNA clone, coding for a novel rhoptry protein PfRhop148, was obtained by antibody screening of a library. The deduced amino acid sequence consists of 1262 amino acids and is highly rich in Asn (22%). The Asn residues are distributed in clusters and in multiple units of repeats. Analysis of specific RNA transcript and protein showed that PfRhop148 was synthesized at around 21 h post-invasion. IFA and immunoelectron microscopic analyses revealed a rhoptry localization for the protein. The role of this protein in invasion and its relationship to the RhopH complex is now under further investigation.