Objective： To investigate the relationship among the latest WHO classification of thymoma, myasthenia gravis （MG） and clinical stages. Methods： To review the pathological sections of 74 patients with thymoma from 1980-2004 using WHO classification （1999）, the statistical software was used to analyze the relationship among the WHO classification, MG and clinical stages. Results： （1） Two cases of type A, 23 cases of type AB, 4 cases of type B1, 27 cases of type B2, 16 cases of type B3 and 2 cases of type C were classified. Type B2 more likely accompanied MG （P〈0.05）, while none with MG occurred for type C. （2） One patient was in stage Ⅰ, 30 were in stage Ⅱ, 38 were in stage Ⅲ, and 5 were in stage Ⅳ. The latest histologic classification was significantly correlated with Masaoka stages （P〈0.01）. Conclusion： The latest WHO classification was correlated with occurrence of MG and finely reflected clinical stage. It can also evaluate the prognosis of patients.
