Eight individual and blended chemical disinfectants were screened for preliminary evaluation of safety, bactericidal and virucidal effectiveness against poultry and dairy organisms. The test organisms were Escherichia coli, Salmonella Enteritidis, Staphylococcus aureus, Streptococcus spp. and Clostridium perfringens, in addition to avian influenza virus (AIV) and Newcastle disease virus (NDV). Viable counts of surviving bacteria were determined after 30 min contact with each disinfectant and in the presence or absence of skimmed milk, to simulate the interference of organic matter. The haemagglutination test was used to assess the survival of the test viruses in the presence of the different disinfectants after propagation in 10-day-old chick embryos. In the presence of skimmed milk, a higher concentration of most of the disinfectants examined was required to exert antimicrobial effectiveness. When used individually, quaternary ammonium showed no virucidal activity against NDV and AIV; peracetic acid was not effective against Streptococcus spp., S. Enteritidis and NDV, while iodophors showed low bactericidal and inconsistent virucidal activity. The single and blended disinfectants with high microbicidal activities included phenols (high bactericidal and virucidal activity), blends of quaternary ammonium compounds (high bactericidal activity) and blends of cresols and organic acids (high virucidal activity). This suggests the use of blends of compatible compounds for disinfection operations in poultry and dairy industries since they will target a wider range of micro-organisms. None of the disinfectants had a negative effect on the development of the different organs of chicken embryos and the iodine-based disinfectant, developed for dairy-teat dipping, also showed no adverse reactions in experimental cows.