Neuromyths are distorted ideas from neuroscience about the brain and learning. This critical review synthesized data from nine educational neuromyth studies that: (a) used a specific established measure, (b) were published in English, and (c) sampled qualified (in-service) teachers. The total sample comprised 5,259 teachers from 16 countries on six continents. All studies were cross-sectional and used convenience sampling. A common finding was that most neuromyths were endorsed or strongly endorsed by teachers; however, most of the studies were methodologically limited. For example, six studies used unrepresentative samples. Further, none of the studies closely considered the potential impact of neuromyths on teaching practices and learner outcomes. Future research must address these limitations and answer the challenging and important questions that remain, including prevention strategies.