A laboratory study was conducted to determine the effect of Allium sativum and Xylopia aethiopica on the growth of Mucor species, Rhizopus stolonifer and Aspergillus niger isolated from deteriorating sweet potato. While 3% (v/v) aqueous extract of Allium sativum and Xylopia aethiopica reduced the growth of the fungi; a combination of 2% each of both plant extracts retarded the growth better. Partial purification of aqueous extract of Allium sativum and Xylopia aethiopica showed that ethyl acetate fraction of the extracts exhibited the highest level of inhibition of growth of the test fungi compared with n-hexane and diethyl ether fractions. Extracts of Allium sativum and Xylopia aethiopica may be substitutes for conventional chemical preservatives in the processing of juices.Key words: Preservative, conducted, isolated, deteriorating, extract, substitute, conventiona