Background: We describe the clinical and color Doppler ultrasound findings in a series of cases of seeding from hepatocellular carcinoma (HCC) observed in patients treated with percutaneous ablation therapy (PAT) over a 15-year period. Methods: We reviewed the clinical and imaging records of 12 patients with cirrhos is (nine men and three women, age range 51-82 years, mean age 63 years) that showed neoplastic seeding from HCC occurring after one or more PAT procedures. Five of 12 cases of seeding were observed as a complication of 1080 PAT procedures (0.46%) performed in 545 patients (0.96%) by two of the authors (L.T., G.F.) over a long period (15 years) at different institutions. The other seven patients had been treated with PAT procedures at other institutions and had come to our attention during post-treatment follow-up. Results: The 12 patients who had seeding nodules had undergone the following PAT procedures: multisession conventional percutaneous ethanol injection (PEI) without anesthesia (four patients), single-session PEI with general anesthesia (three patients), single-session PEI w ith general anesthesia plus multisession conventional PEI (four patients), and s ingle-session PEI plus radiofrequency ablation (one patient). Seeding nodules r anged from 0.9 to 6.0 cm (mean 1.7 cm). Eleven of 12 seeding nodules appeared as hypervascular hypoechoic nodules with smooth and regular margins and multiple i ntralesional vascular signals. Conclusions: Clinical and imaging findings of see ding from HCC should be recognized by physicians who perform follow-up ultrasou nd examinations of patients who are treated with PAT. Early diagnosis of seeding can be reliably made by scanning the abdominal wall with small probes in the area where the previous PAT has been performed. Hypoechoic hyperva scular pattern of the seeding nodule allows definitive diagnosis. Background: We describe the clinical and color Doppler ultrasound findings in a series of cases of seeding from hepatocellular carcinoma (HCC) observed in patients treated with percutaneous ablation therapy (PAT) over a 15-year period. Methods: We reviewed the clinical and imaging records of 12 patients with cirrhos is (nine men and three women, age range 51-82 years, mean age 63 years) that showed neoplastic seeding from HCC occurring after one or more PAT procedures. Five of 12 cases of seeding were observed as a complication of 1080 PAT procedures (0.46%) performed in 545 patients (0.96%) by two of the authors (LT, GF) over a long period (15 years) at different institutions. The other seven patients had been treated with PAT procedures at other institutions and had come to our attention during post-treatment follow-up. Results: The 12 patients who had seeding nodules had undergone the following PAT procedures: multisession conventional percutaneous ethanol injection (PEI) withou t anesthesia (four patients), single-session PEI with general anesthesia (three patients), single-session PEI w ith general anesthesia plus multisession conventional PEI (four patients), and single-session PEI plus radiofrequency ablation (one patient). Eleven of 12 seeding nodules have been as hypervascular hypoechoic nodules with smooth and regular margins and multiple i ntralesional vascular signals. Conclusions: Clinical and imaging findings of see ding from HCC should be recognized by physicians who perform follow-up ultrasou nd examinations of patients who are treated with PAT. Early diagnosis of seeding can be sure made by scanning the abdominal wall with small probes in the area where the previous PAT has been performed. Hypoechoic hyperva scular pattern of the seeding nodule allows definitive diagnosis.