With the use of grain comes a variety of parasitic fungi – some benign, others dangerous and even toxic. Here are surveyed some of the fungi to which ancient and modern grain is subject, and some of the consequences for human populations. More specifically, several parasitic fungi, Claviceps, purpurea, C. Paspali, Ustilago maydis and U. esculenta, have infested cereal grains and grasses in ancient and recent times and may have served as a source of human foods or medicine.