Aflatoxin is a naturally occurring carcinogen produced by the fungus Aspergillus, particularly Aspergillus Flavus and Aspergillus Parasiticus. Aflatoxin contamination places an economic and health burden on farmers throughout the developing world, but reliable prevalence data are difficult to obtain. This report analyzes data from 25 primary research articles published within the last 15 years in order to provide a summary of aflatoxin contamination in the developing world. This report is divided into three parts, roughly aligning with phases of the agricultural value chain. Data for prevalence at the production and processing stage are presented first, followed by data for prevalence during storage, and finally by a summary of data for aflatoxin levels at consumption and point-of sale. We find maize and groundnuts to be the crops most affected by aflatoxin, while Southeast Asia and Sub-Saharan Africa are the geographic areas most likely to be affected. Agroecological conditions including warm humid climates, irrigated hot deserts, and droughts contribute to aflatoxin contamination, and we find that contamination can occur throughout the value chain.