The use of fine needle aspiration biopsy (FNAB) in the diagnosis of many lesions in different parts of the body is quite widespread, while it has been used for oral lesions only very recently. This technique has many advantages including ease of use, cost effectiveness, convenience and accuracy. The present study, investigated the diagnostic value of FNAB in solid oral lesions using, specimens from 90 patients (56 females, 34 males), with ages ranging from 7-70 years which were examined in comparison with their histopathological sections. Cytological specimens were evaluated based on the presence of diagnostic cells. Ninety cases were divided into two major groups those with fibrous and nonfibrous lesions, for the the purposes of histopathological diagnosis. Among all fibrous lesions, cytological diagnosis was possible in 20 cases, whereas 45 out of 49 non-fibrous oral lesions yielded diagnostic cells. In conclusion it was shown that FNAB was not very diagnostic in fibrous lesions. However, in lesions with loose stroma, rich in vessels or inflammatory cells, and in malignant tumors, FNAB was a very successful method which yielded a correct diagnosis. (J. Oral Sci. 41, 41-45, 1999)