Dendritic cells (DCs), the most potent antigen-presenting cells in vivo, are now used for cancer immunotherapy during which they are usually administered to the blood of patients with cancer. However, the route of administration of DCs affects the magnitude of immune responses. This study was conducted to assess the safety of the direct administration of DCs into cancer nodules. DCs were generated by culturing peripheral blood mononuclear cells with granulocyte-macrophage colony-stimulating factor and interleukin-4 for 7 days. After confirming the phenotype and function, one hundred thousand DCs were injected directly into the cancer nodules of 4 patients with hepatocellular carcinoma (HCC) under ultrasonography guidance 48 h after the administration of 100% ethanol. All patients were monitored for any alteration in generalized condition, signs of inflammation, and liver and kidney function for the next 14 days. In addition, the final assessment of the safety of the administration of DCs into cancer nodules was performed 6 months after therapy commencement. The injection of 100% ethanol disrupted the HCC nodules in all 4 patients. DCs were distributed uniformly in the cancer nodules as assessed by ultrasonography. The administration of DCs into cancer nodules was well tolerated by all patients and there were no immediate or delayed side effects. The tumor marker decreased in one patient after the direct administration of DCs. Direct administration of DCs into the cancer nodules of patients with HCC was safe.