This study was undertaken to evaluate safety and antitumor activity of Nexia, a processed extract of Rhus verniciflua STOKES by heating according to Korean patent 0504160 through toxicology, cancer research and clinical application. Nexia did not exhibit any toxicological symptoms through 13 week continuous treatment, dosage accumulation study and anaphylaxis response. The lifespan of four patients with acute lymphocytic leukemia under complete remission were 110, 83, 97, and 86 months after treatment of Nexia, respectively. These data suggest that Nexia, a processed extract by removing allergen from Rhus verniciflua STOKES, may have safety and antitumor activity and also still need continuous study on its mechanism and clinical trial.