Ortho-phthalaldehyde (OPA), a high-level disinfectant alternative to glutaraldehyde, was tested for efficacy against human hepatitis B virus (HBV) and hepatitis C virus (HCV) using surrogate animal viruses. HBV and HCV are the most prevalent human bloodborne viruses but have not yet been propagated in the laboratory. The surrogate viruses, duck hepatitis B virus (DHBV) and bovine viral diarrhea virus (BVDV), were used to assess the virucidal efficacy of OPA on HBV and HCV, respectively. After a timed exposure to the test disinfectant, the surrogate virus dried on a hard surface was neutralized and assayed to detect viable viruses using appropriate cell lines. A greater than 4-log(10) reduction in virus titer was demonstrated using dilute OPA solutions against dried DHBV and BVDV after 5 minutes of exposure at 20 degrees C. OPA was shown to be efficacious against surrogate viruses for human hepatitis B and hepatitis C virus. This is the first time that OPA efficacy has been demonstrated for HBV and HCV.