Background: Class II malocclusion is a dental problem where the upper and lower jaws don't align properly. This study compares two methods, the BIBRE technique and modified Twin Block appliances, to treat Class II patients with a backward-positioned lower jaw. The goal is to find out if there are any noticeable differences in the results of these treatments. Aim: Comparative Evaluation of Skeletal and Dentoalveolar Effects of Bonded Inclined Bite Raiser Elastic (BIBRE) and Modified Fixed Twin Block Appliances in Skeletal Class II Patients with Retrognathic Mandibles .Material and methods: The study examined individuals who opted for fixed orthodontic treatment involving mandibular advancement. The sample size of 20 (10 in each group) was determined based on a previous study, taking into account a standard deviation of ±2, a 95% confidence interval, and 80% study power. Cephalometric analysis evaluated maxillomandibular relations using 12 skeletal parameters, 5 dentoalveolar parameters, and 2 transverse parameters. The control group used the fixed twin block appliance, while the experimental group used the bonded inclined bite raiser elastic appliance.. Results: The Fixed Twin Block Appliance and BIBRE Appliance groups showed significant results. Skeletal parameters, including Beta angle, SNA, SNB, ANB, Effective mandibular length, Y-axis, Mandibular plane angle, Saddle angle, Gonial angle, Lower gonial angle, Articular angle, and Facial axis angle, had notable differences before and after treatment in both groups. Dento-alveolar parameters also exhibited significant changes. However, the differences in SNA and Gonial angle between pre and post-treatment were not statistically significant. When comparing the two groups, the control group (Fixed Twin Block) had higher values in Beta angle, SNA, Effective mandibular length, Gonial angle, Lower gonial angle, and Facial axis angle compared to the experimental group (BIBRE). Conclusion The study evaluated the effectiveness of Fixed Twin Block appliance and BIBRE therapy for treating class II malocclusion. Both treatments restrained maxillary growth and increased mandibular length. The Fixed Twin Block appliance showed significant effects on upper incisors and inter-canine width.