This paper examines the relationship between misinformation about product quality and quality standards, such as minimum quality standards and certification criteria, when products are vertically differentiated in their health/safety aspects. We investigate the welfare effect of regulating misinformation and strengthening MQSs. We find that when the amount of misinformation on both low-and highquality products is small, regulating misinformation on low-quality products reduces welfare, although the strictness of an MQS influences its effect. On the other hand, regulating misinformation on high-quality products always improves welfare. We also find that a stricter MQS can harm welfare. This, in particular, is likely to occur when the difference between the perceived quality of the two types of products is large and when firms generate high degrees of misperceptions. Moreover, we extend the analysis by endogenizing quality investments and demonstrate that regulating misinformation on high-quality products may deteriorate their true quality and, thus, reduce welfare.