Heavy metal contamination in soils is a major environmental concern that affects large areas worldwide. Agricultural practices have been the main source of heavy metals in soil such as lead, chromium, arsenic, zinc, cadmium, copper and nickel. Plants can uptake this toxic metals and have evolved defense mechanisms to avoid or minimize damages. Exposure to toxic metals can intensify the production of reactive oxygen species (ROS), which are continuously produced in both unstressed and stressed plants cells. Some of the ROS are highly toxic and must be detoxified by cellular stress responses, if the plant is to survive and grow. Heavy metals contaminated plants cause losses in crop production and risks for human health. Thus, this review aims to compile some information about research work on concentration of heavy metals until they reach the food chain for transferring to crops.