Fine needle aspiration biopsy has been documented as areliable, cost effective test, diagnosing different thyroidlesions. However, its sensitivity declines much in somesettings.Objectives: to investigate the value of computerizedmorphometry and DNA ploidy in differential diagnosis ofdifferent thyroid epithelial follicular lesions diagnosed onFNA smears.Study design: 34 cases of thyroid FNA were cytologicallyexamined, and classified according to their postthyroidectomyhistopathological diagnosis as follow: 5cases of nodular goitre, 7 cases of adenomas, 5 cases offollicular carcinoma, 10 cases of papillary carcinoma, 5cases of anaplastic carcinoma and 2 cases of poorlydifferentiated carcinoma. Using Leica Qwin 500 imageanalysis system, nuclear area as a morphological variable, aswell as the DNA ploidy, DNA index, and proliferationindices were measured for each case.Results:sensitivity of FNA in the studied cases wasoptimum (100%) in papillary carcinomas and anaplasticcarcinomas. However, the sensitivity declined sharply indiscriminating nodular goiter and follicular adenoma fromwell differentiated follicular carcinoma, most of these caseswere diagnosed as follicular lesions. A significant differencein mean values of nuclear area was found between benignand malignant lesions, with no statistical differences withinthe benign group. Aneuploidy and DNA index (DI) weresignificantly associated with malignancy. Proliferationindex (PI) was significantly higher in the malignant lesionswith no statistically significant difference between thediagnostic groups. Conclusion: image analysis maybecome an important ancillary test in the initial evaluationof patients with thyroid epithelial lesions.Key words: morphometry, DNA cytometry, image analysis,thyroid follicular lesions, proliferation index, DNA ploidy