In this study, we investigated the in-vitro antimicrobial activity of some medicinal plants in the Arabian peninsula, including Rhamnus globosa, Ocimum basilicum, Tecoma stans and Coleus forskohlii. Our results showed high inhibitory growth in yeast after treatment with R. globosa and O. basilicum. C. tropicalis was shown to be a sensitive strain with an inhibition of 29, 28, 35, 25 and 27 mm after treatment with R. globosa, R. globosa* "leaf with thorns," O. basilicum, Tecoma stans and Coleus forskohlii, respectively. Thus, our results confirmed the fungicidal effect of O. basilicum and R. globosa with a 20 and 30% reduction in CFU compared with the starting inoculums in the time-kill.