Foliar fertilization is a widely used method used to supplement soil applications to improve the yield and quality of cotton. It has the advantages of low cost and a quick plant response, and it is particularly important when soil problems occur and root growth is inadequate. On the other hand, it has disadvantages of possible foliar burn, solubility problems, and only a small amount of the nutrient can be applied at any one time. Variable yield responses to foliar fertilization have been reported. These are probably associated with incorrect timing of applications, the use of inappropriate fertilizer materials, and insufficient attention to soil available nutrients, the size of the boll load, and environmental conditions. The efficiency of foliar fertilization can be influenced by the type of fertilizer, concentration and pH of the solution, the use of adjuvants, and compatibility with other agrochemicals. Attention also needs to be given to the ideal method and timing for incorporation of foliar fertilization into existing production practices.