An experimental greenhouse campaign was conducted to evaluate the effect of arbuscular mycorrhizal fungi (AMF) on the production of essential oils in rosemary (Rosmarinus officinalis L.). For effect, a completely randomized experimental design was implemented, with three treatments composed of soil plus multisporic inoculum (Glomus spp, Acaulospora spp, Entrophosfora spp, Scutellospora spp.), soil plus monosporic inoculum (Entrophosfora colombiana), and the control treatment without inoculation, all of these with ten replicates per treatment. The soil used for all experimental units was sterilized and adjusted to 0.02 mg L-1 of P (phosphorus), the optimum concentration for the mycorrhizal condition. The response variables were: foliar P content, aerial dry mass, mycorrhizal colonization, and essential oil yield. The results of aerial dry mass indicate significant increases in the inoculated treatments compared to the control treatment. Leaf P showed no differences between treatments. The average mycorrhizal colonization of the inoculated treatments was 73%. As for the essential oils produced by the rosemary plants, the results were the inverse of those of the mass, where a higher yield was found in the control treatment. According to the data, the use of HFMA in the production of rosemary favors the development of the plant; on the other hand, the yield of essential oils could be compensated by the higher biomass produced, which would allow producers to increase the amount of oil extracted. Keywords: essential oils, arbuscular mycorrhizal fungi, Rosmarinus officinalis.