We evaluated the presence of abdominal organomegaly and lymphadenopathy with ultrasound in 92 children with acute lymphoblastic leukemia (ALL) prior to chemotherapy, and compared these findings with the different immunophenotypes, age groups, and white blood cell (WBC) counts as well as the survival of the patients and the clinical findings of organomegaly. All the patients (n = 13) with a WBC higher than 50/microL showed intra-abdominal pathology compared with the patients with a low WBC, of whom 37% (n = 18) had normal scans. The children with a high WBC count also had hepatomegaly (P = 0.003) and splenomegaly (P = 0.06) significantly more often, and showed high echogenicity of the kidneys (P = 0.001). Lymphadenopathy was found significantly more often in children with T-cell leukemia (P = 0.005). The younger age groups (0 to 2 and 2 to 5 years of age) had hepatomegaly significantly more often (P = 0.02), and the youngest age group (0 to 2 years) showed increased echogenicity of the kidneys more often (P = 0.04). Ultrasound showed hepatomegaly in 14 patients and splenomegaly in 23 patients who were assessed clinically as normal. According to our results, abdominal ultrasound is a useful tool for evaluating abdominal organomegaly and the extramedullary leukemic burden and can give information that is not available in clinical examination. There was no statistical association between the primary ultrasonographic findings and the patients' later survival.