Objective To evaluated diagnosis yield of cytological and histological analysis of endoscopic ultrasound guided fine needle aspiration (EUS-FNA).Methods A total of 43 patients who were clinically diagnosed as having mediastinal lesions,retroperitoneal lesions or pancreatic lesions by CT were recruited to the study.EUS-FNA was performed with standard 22G needle.Specimens were placed in formalin for histological analysis,and residual materials were prepared for cytologic analysis.Results Lesions were located in the mediastinum (n =9),the retroperitoneum (n =1),and pancreas (n =33).Cytologic diagnoses included malignancy (n =22),suspicious malignancy (n =2),atypical cell (n =3),absence of malignancy (n =16).Histologic diagnoses included malignancy (n =30),suspicious malignancy (n =1),sarcoidosis (n =2),chronic inflammation (n =10).The positive rates,sensitivities and accuracies of cytology and histology were 51％,59％,65％ and 74％,81％,84％,respectively.Conclusion The positive rate,sensitivity and accuracy of histology of EUS-FNA is superior to cytology.