The female Anopheles gambiae s.l is the principal intermediate host/vector of Plasmodium - the causative organism of malaria fever in many tropical countries. After a preliminary acute toxicity screening of leaf extracts of Hyptis suaveolens using descending series of concentrations (1000 500, 100, 50 and 5 μg/m ), two extracts (aqueous and ethanolic ) were assayed against freshly laid eggs and larval instars of An. gambiae following the standard World Health Organisation ovicide and insecticide susceptibility bioassay methodology. The results indicate that both ethanolic and aqueous extracts of the test plant significantly (F = 30 23, df = 5, p < 0.01; F = 45.28, d = 5, ρ < 0.01 respectively) reduced the viability of the An. gambiae ova exposed to different doses of the extracts. In the ovicidal assay the lethal inhibition doses of egg hatching (IH₅₀