Introduction: There is a growing concern that overloaded children’s backpack and messenger bag may lead to the development of musculoskeletal injuries. Forward head posture and protracted shoulder are two most common deformities causing postural deviations resulting from frequent carrying of heavy backpacks and messenger bags by children and adolescents. Aim. This study is therefore aimed to compare the effect of backpack and messenger bag on the Craniovertebral angle (CVA) of secondary school students in selected local government’s areas in Lagos State, Nigeria. Methods: Two hundred (110(55%) females and 90(45%) males) secondary students participated in this study. They were within the age range of 10-18 years. Participants were randomly assigned into 2 groups: (group1-Back pack and group2-messenger bag) using computer generated number sequence. The CVA was obtained and was recorded photographically under several load-carrying conditions. Result: There was statistically significant difference (p=0.000) in the CVA when the backpack or the messenger bag was careried with 15% of their body weight for both type of bags. There was also statistically significant difference (p=0.000) in CVA when the backpack or the messenger bag was carried and the participants were placed on a form of brisk walking for 5minutes with the backpack/ messenger bag and the additional 15% weight. Conclusions: This study concluded that both the backpack and the messenger bag caused a significant change in the CVA of the participants when carried. Carrying schoolbags weighing ≥ 15% of body weight appeared to be too heavy to maintain normal standing posture for school students.