This work is part of the fight against in vitro the growth of Lasiodiplodia theobromae with some medicinal plants including Aloe vera, Moringa oleifera and Newbouldia laevis. This fungus causes brown cocoa rot in the Kisangani region. The antifungal activity of the crude, aqueous, ethanolic and ethereal extracts of fresh and dried leaves of the plants studied were evaluated in vitro by six repetitions on Potato dextrose agar medium. After two days of incubation, the raw extract of the fresh leaves of M. oleifera inhibited the growth of L. theobromae by up to 74.1% followed by that of A. vera (29.6%) and N. laevis (14.7%). The aqueous, ethanolic and ethereal extracts of the fresh leaves of M. oleifera revealed respective inhibition percentages of 43.0; 53.3 and 71.1. As for the extracts of the dry leaves, A. vera was active with its ethereal extract (58.1%) and ethanolic extract (56.7%). Notwithstanding, M. oleifera remains the very active plant with an excellent inhibition rate of 74.1% having considerably slowed down the maximum growth time of L. theobromae by reducing it from two days for the control to six days for the raw extract. Although the plant extracts studied have a fungistatic effect, their purification by extraction of phytochemical groups in our next studies, could reveal their respective fungicidal properties.