Pre-fabricated re-mouldable myofunctional appliance (T4F) has been introduced for correction of Class II malocclusion, however very few studies have been reported on the effectiveness of myofunctional appliances. The aim of this study was to compare the changes in the skeletal and dentoalveolar structures in growing patients with Class II Division 1 malocclusion treated T4F and Twin Block appliance (TB). A randomized clinical trial was carried out with a sample of 23 subjects randomly assigned to active control group (TB) and experimental group (T4F). Mean age was 13 years (SD=0.7) and 13.2 years (SD=0.8) in T4F and TB group respectively. Overjet assessment and lateral cephalometric analyses were performed before and six months after intervention. Twenty angular and linear measurements were measured. The changes during the study period were calculated by comparing pre and post treatment measurements in each group. From this study we observed there is significant difference (p value <0.05) in the OJ, SNB, ANB, Sv_Pog, Sv_ii and is_ii with more favourable changes in TB group. The results suggest that T4F appliance is an effective appliance for the management of Class II Div.1 malocclusion but may need longer treatment period than TB appliance.