Forty patients with suspected malignant disease of the liver underwent percutaneous fine-needle aspiration biopsy with radioisotope scintigraphic and fluoroscopic guidance. The needle was aimed at focal defects identified on the liver scan and several passes were made. When the scan was diffusely abnormal, the liver was widely sampled with multiple passes. Thirty patients were eventually considered to have malignant disease and aspiration biopsy was positive in 28 (93%) of these patients, including 25 of 26 with liver metastases (96%). There were two false-positive results and one minor complication. In 24 patients, conventional wide-bore needle biopsy was also performed. In this group, 16 patients had a final diagnosis of hepatic malignancy. Aspiration biopsies were positive in 14 of these (87%) and conventional needle biopsies were positive in four (25%). Guided percutaneous fine-needle aspiration biopsy is recommended for pathologic diagnosis of hepatic malignancy because of its simplicity, high yield, and reasonable safety.