One hundred sixty-nine children suspected of having malignant disease were examined by Ga-67 scintigraphy. In 99 children with untreated diseases at the time of examination, abnormal accumulation of Ga-67 was found in 51 patients, including 40 with malignant tumor. Forty-three negative results were obtained in children with benign disorders. Five false-negative results were obtained in patients with neuroblastoma of the adrenal gland. In 70 children with malignant diseases treated before the examination, abnormal accumulation of Ga-67 was seen in 40 patients, including 38 with malignant disease and two with no clinical evidence of recurrence. Normal results were obtained in 30 patients, including 11 still suffering from malignant disease. The results of Ga-67 scintigraphy in all of the children were evaluated qualitatively. For the final diagnosis of malignant disease, diagnostic specificity was 86% and diagnostic sensitivity 79%. The prevalence of malignant disease was 56%. It is concluded that Ga-67 scintigraphy should be used for primary visualization and control of malignant tumors in children.