Anopheles culicifacies , the major vector of malaria in Sri Lanka, and An. subpictus , a secondary vector, exist as species complexes in the country. Among the globally reported five sibling species (A-E) of the An. culici- Jacies complex, only species B and E have been detected in Sri Lanka. However, all four sibling species (A-D) of the An. subpiclas complex present globatly are found in Sri Lanka. Thi s article reviews the data on the characteris- tics of the sibling species of these two main malaria vectors in Sri Lanka and methods for differentiating them, and highlights the importance of understanding the bio-ecological variations among the sibling species in order to de- velop an effective vector control program in the country. It is proposed that An. culicifacies species E may have evolved from species B in Sri Lanka and then spread to South India. The development ofDNA probes suitable for differentiating the sibling species of An. culicifacies and An. subpictus in field studies is identified as a particular priority for future work.