We investigate the spread of substandard fertilizer in the market and its possible consequence on the application and the agricultural performance in Southeast Asia and sub-Sahara Africa. Low quality fertilizer discourages farmers to adopt modern technologies, and this leads to stagnant productivity growth. Based on careful observations and quantitative evidence from field surveys, we discuss the potential causes and consequences of the prevalence of substandard fertilizer. We also examine the role and effectiveness of the regulations and inspection institutions in dealing with this widely observed issue. Our goal is to provide valuable information and implications for the policies to address the problem of substandard inputs in the developing world.