This paper provides a synopsis on various studies conducted on adoption of improved maize varieties in developing countries, particularly Africa and South Asia, during last fifteen years. The studies have pointed out a number of socio-economic characteristics, agro-ecological variables, and farmers’ perception as important determinants of improved maize varieties in different countries. Among these variables, extension contact, education, farm size, credit availability, use of fertilizer, low land area, yield and profitability are found to be major determinants which have strong positive influences. The adoption studies are found more focused to socio-economic variables in comparison to agro-ecological variables and farmers’ perception. Researchers are suggested to consider these variables as important as the socioeconomic variables in any adoption studies of agricultural innovations.