Objective To investigate the relationship between pelvic asymmetry and Crowe classification of unilateral developmental dysplasia of the hip in adults. Methods According to the inclusion criteria, 100 cases of unilateral DDH in adults were collected, including 78 females and 22 males, with an average age of 56.3 years old (range, 21-79 years). In terms of Crowe classification, there were 30 cases of Crowe typeⅠ, 24 cases of Crowe typeⅡ, 23 cases of Crowe typeⅢ, and 23 cases of CroweⅣ. The normal?side and affected?side pelvic vertical height (the distance from the highest point of the ischial tuberosity to the iliac crest peak) were measured via the radiogram of anteroposterior pelvis. Furthermore, we compared the affected?side pelvic vertical height with the normal?side and analyzed the relationship between Crowe classification and the difference in pelvic verti?cal height. Results The average pelvic vertical height was 23.38±1.46 cm in the normal?side and 22.41±1.38 cm in the affected?side. The average D?value of pelvic vertical height between two sides is 0.98 ± 0.76 cm. From Crowe typeⅠto Ⅳ, the average heights of the normal?side were 22.89±1.09 cm, 23.23±2.07 cm, 23.75±1.16 cm, 23.79±1.22 cm, while those of the affected?side were 22.70 ± 0.98 cm, 22.41 ± 1.98 cm, 22.47 ± 1.12 cm and 21.92 ± 1.32 cm. The average D?values in each group were 0.19 ± 0.37 cm, 0.82±0.43 cm, 1.28±0.32 cm, 1.87±0.59 cm. The differences between the normal?side and the affected?side in each type were statistically significant. The average D?value increased significantly with Crowe type increased, and there was a positive correla?tion between the D?value of bilateral pelvic vertical height and the degree of hip dislocation. Conclusion The pelvic asymmetry does exist in adult patients with unilateral developmental dysplasia of the hip. Moreover, the asymmetry has positive correlation with the degree of hip dislocation.