The contributions of microorganisms in the deterioration of African breadfruit during storage were investigated in this study. Matured fruits of the seedless variety of the African breadfruit (Artocarpus communis, Forst) were stored under different temperature conditions and morphological changes observed at 24-h intervals for 120 h. Spoilage of breadfruit was observed after 72 h with microbial growth. Although all the fruits in the different media deteriorated by the 72nd hour (this was revealed in morphology and confirmed by the proximate analysis which showed an increase in %crude protein in all the stored fruits), microbial growth was observed only in those fruits stored at room temperature and in water, and there was no significant microbial growth in fruits stored in refrigerator, freezer, and vinegar. A higher rate of deterioration (i.e., higher %crude protein) was observed in morphology of fruits which had microbial growth during storage (i.e., those stored in the room, under water, and refrigerator) than in those stored fruits with no significant microbial growth. The difference between the %crude protein in fruits where there is microbial growth and that of the fruits where there is no microbial growth (i.e., freezer and vinegar) proved to be significant (P ≤ 0.05). The study thus reveals that microorganisms play a substantial role in the spoilage of African breadfruit. A strain of the Aspergillus sp., two strains of the Penicillium sp., and a strain of the Molinia sp. were isolated as fungal spoilage organisms. Bacillus sp. and Pseudomonas sp. strains were isolated as bacteria spoilage organisms.