Elionurus hensii yields essential oils composed mainly of para-menthadienols in its stems and about 50 % aristo lone in its roots. These oils, which exhibit anti-microbial and anti-oxidant properties, were extracted by hydro distillation with a local extractor and was analyzed by gas chromatography (GC/FID and GC/MS). To optimize this domestic process, a 23 full factorial design is used to assess the effects and interactions of potentially influential factors. Stems yield 1-2% in essential oil. The extraction time and the degree of division of the plant material had negligible effects on the yield. Only the residual water content had a significant positive effect, together with the interaction between this content and the degree of division. The cumulated content of the four isomeric para-menthadienols present in the oil was insensitive to the effects and interactions of the factors. Roots yield 0.5 - 0.9 % in essential oil. The overall effects and interactions of factors on the yield and the aristo lone content were negligible. Principal component analysis of samples obtained with the experimental design, and their radar plots, indicated a very strong resemblance between oils obtained from the same plant part, and a marked difference between those obtained from different plant parts.