Results of 70 fine-needle aspiration biopsies (FNAB) were evaluated retrospectively in 61 pediatric patients. Over a period of 9 months all mass lesions suspected being malignant were aspirated. Twelve of the 70 aspirations were performed in children having known tumours, in order to exclude recurrence or metastasis. The others were carried out to obtain a diagnosis. Satisfactory specimens were obtained from 58 (83%). There were 21 benign diagnoses, 36 malignant diagnoses, and 1 with suspected malignancy. Correlation of histologic and cytologic diagnoses was possible in 45 cases. The diagnostic sensitivity and specificity were 95% and 80%, respectively. We have found FNAB more accurate in the diagnosis of malignancies than in benign lesions. The results suggest that this is a useful technique for obtaining a first diagnosis of malignancy, as well as for excluding recurrence or metastatic disease.