Deep curve of spee is associated with lower anterior crowding and deficient mandible and the treatment gets difficult when twin block is used alone as it does not increase arch length significantly and so lip bumper was added which helps in relieving lower anterior crowding by distalization and/or preventing mesial movement of molar. Aim: To evaluate and compare the skeletal and dental effects of Twin Block with Lip Bumper and Twin Block. Study Design: Retrospective study was carried out in 34 patients (20 females and 14 males). They were divided into two groups: group A (Twin Block) and group B (Twin Block with Lip Bumper) on the basis of functional appliance used. Results: Comparison between the age of the patients among both the groups was done using unpaired t-test and between gender was done using chi square test. No significant difference was seen among the both groups in terms of age and gender (p-value is >o.o5). Significant difference is observed in skeletal and dental parameters before and after the treatment in group A and group B. On comparing between both groups, highly significant difference is seen wrt change in lower incisor position and SNB angle and significant difference was seen wrt FMIA and corpus length (Go-Pog). It was more evident in group B than in group A. Conclusion: For group A, significant change is seen in position of mandible anteroposteriorly along with acceptable changes wrt anterior and posterior facial height. For group B, along with changes in mandible anteroposteriorly marked changes where seen wrt inclination of lower incisors, molar inclination and corpus length. On comparing between group A and B, highly significant difference was seen wrt to anteroposterior positioning of mandible, lower incisor inclination, molar inclination and corpus length and it was more evident in group B than in group A.