Poor quality fertilizer is a growing problem in many countries. This is of special concern to smallholder farmers as they have neither the buying power nor the testing instruments to verify the authenticity of the input. We analyze the effect of fertilizer quality on its use intensity. This study distinguishes between perceived quality and true quality. Results show that perception of higher quality reduces fertilizer application rates. However, the true quality measure based on laboratory testing of fertilizer samples has no statistically significant impact on fertilizer use intensity. There is also no significant correlation between true and perceived quality.