Background To determine the difference in the rate of myopic progression between children wearing single vision lenses with undercorrection of +0.50D and children whose myopia is fully corrected, and to explore the factors that may influence the process. Design Randomized, controlled, double-blind trial. Participants Two hundred children aged 7-15 years with low-to-moderate myopia (-1.5D to -6.0D), astigmatism <-1.5D and anisometropia <1.0D. Methods The children were randomly allocated to wear single vision lenses with full correction or undercorrection by +0.50D. Ocular examinations and questionnaire surveys for myopia-related factors will be performed every 6 months. Main Outcome Measures Cycloplegic autorefraction and axial length. Results Of 200 children, 100 (50%) were girls, 41 (21%) esophoric and 82 (42%) exophoric at near. The characteristics of gender, age, age of myopia onset, phoria, eye dominance, parental myopia, refractive error, axial length, corneal curvature, mean time spent in near work and outdoor activities between the two groups were not significantly different. The accommodative responses at 33cm, the accommodative demands and lags at infinity were significantly different in the two groups as they were measured with full correction in one group and undercorrection in the other. Conclusion Full correction and Undercorrection of Myopia Evaluation Trial is a clinical trial designed to determine the effectiveness of undercorrection of myopia by +0.5D on myopic progression in a population of school-aged children known to be susceptible to myopia and to identify the factors influencing the process.