Three pediatric patients with tumors (2 rhabdomyosarcoma, 1 Wilms tumor) had significant focal defects on 99mTc S colloid scans while receiving chemotherapy (all 3 had received chemotherapy, including actinomycin D, within 10 days prior to scanning). In all 3, the defects resolved spontaneously; 1 biopsy showed fibrosis of a mild degree. The finding of defects on liver scans of pediatric patients receiving chemotherapy must not be automatically assumed to be metastatic disease; the changes may relate to hepatic response to recently administered chemotherapy.