Introduction: A parallel design randomized clinical trial was conducted to compare dentoalveolar and skeletal changes in two groups of patients who had completed twin block therapy; one group had a three-month night-time retention period whereas the other group had no retention period, after twin block therapy but before fixed appliances. Methods: 26 participants of Malay ethnicity aged 10 to 15 years were included in the trial and had an overjet of 5mm or greater, molar relationship greater than half cusp Class II on a skeletal Class II base which had been corrected to a Class I molar relationship following twin block therapy. Following randomization, the 26 were divided into two groups of 13. Group A had fixed appliances bonded immediately whereas group B continued wearing twin block at night for three months, after which fixed appliances were bonded. Lateral cephalograms assessed were those taken before randomization, upon twin block therapy completion (T1) and six months after bond-up of fixed appliances (T2). Results: Paired t-test showed several statistically significant dentoalveolar and skeletal changes in group A. In contrast, only condylar head position exhibited a statistically significant change in group B. Despite a statistical significance, changes measured in both groups were minimal at less than 2mm and therefore clinically insignificant. Independent t-test showed no statistically significant difference between the changes recorded in both groups. Conclusion: The results suggest that a three-month night-time retention period after twin block therapy does not lead to any changes that may be considered clinically beneficial.