Objective：To investigate the status of wedge-shaped defects among adults in Ningxia，thus to provide clinical references for the prevention of this disease. Methods：Totally 4 064 adults in Ningxia were investigated in this study according to the criterion issued by China oral health epidemiology survey protocol. The incidence and therapy rate of wedge-shaped defects in different groups were calculated. SPSS 11.5 statistical software was applied to analyze the results. Results：①The overall incidence of wedge-shaped defects was 42.67%. The incidences were increased with the growth of age and there were significant differences among different age groups. It was peaked at the age between 50 and 59，but was decreased at the age between 60 and 69 and more than 70. The over－all therapy rate was 15.63%. The therapy rates were reduced with the growth of age and the differences were statistically significant among different age groups. ②The incidence was higher in male than in female without statistical differences. The therapy rate was high in male than in female with statistical differences. ③The place with the highest incidence of wedge-shaped defects was the first premolar（15.59%），while that with the lowest incidence was the second-molar（0.26%）. The differences in the different teeth were statistically significant. The incidence of wedge-shaped defects was higher in maxilla teeth than in mandible teeth and the incidence was higher in the left teeth than in the right teeth with significant differences. The therapy rate of the first premolar was the highest，and the differences in the different teeth were statistically significant.④The method of teeth-brushing was significantly related with wedge-shaped defects. Conclusions：The incidence of wedge-shaped defect is related with tooth location and age in Ningxia. Its incidence is higher than the therapy rate. So it is necessary to strengthen the propaganda of oral cavity of prevention and protection for adults in urban of Ningxia.