Abstract: Objective: To investigate the diagnostic value of X-ray,CT and MRI in acute avulsion fracture of tibial tuberosity in adolescents.Method: 6 cases(all male) of acute avulsion fracture of tibial tuberosity in adolescents confirmed by operation were analyzed retrospectively.Of them,2 cases and 4 cases were right side and left side,respectively.5 cases were caused by sport injury and 1 case was tumble injury.6 cases all received X-ray examination,2 cases underwent plain CT scans and 3 cases underwent conventional MRI scans.Results: According to Ogden's classification,the case of type ⅠB,ⅡA,ⅡB,ⅢA,ⅢB were 1,1,2,1,1 respectively on X-ray film.The sign of patella on the shift was found in all cases.CT scanning showed displacement of bone fragmenets and patella on the shift in 2 cases of type ⅡB,and 1 case was complicated with old fracture of patella.3 cases were complicated with patellar tendon ruptures.In 1 case of type ⅡB complicated with patellar tendon ruptures,CT and MRI showed that patellar tendon was swollen and twisted,and was high signal intensity on T1WI and T2WI.Conclusion: X-ray was the first choice for imaging diagnosis in acute avulsion fracture of tibial tuberosity and CT is helpful for the fracture classification.MRI has an important value in diagnosis and guiding treatment when suspected that complicated with soft tissue injuries,such as patellar tendon,meniscus tear and so on.