The germicidal activity of commercial teat dip formulation (cyteal) (contaning 0.1 g hexaidine, 0.5 ml chlorhexidine digluconate and 0.30 g chlorocresol) was tested in vitro against Staphylococcus aureus, Streptococcus and corynebacterium bovis field strains isolated from dairy herd of 78 lactating cows. It was revealed that a concentration of 0.5% tested compound was effective against the isolated organisms. a natural exposure study was conducted for 6  months in dairy herd to determine the efficacy of cyeal as post-milking teat antiseptic for the prevention of the new intrammary infections. there were 7.4% new intrammary infections on the dipped group and 21.6 on the control group, 65.7% reduction). The teat dip was effective in preventing new infections with Staphylococci,, strept. agalactiae, Corync . bovis but did not appear to prevent new infection with coliforms. the percentage of infected quarters on the dipped was reduced from an initial (35.1%): to 22.2%) at the end of the study whereas the incidence in the control quarters increased from milk (23.6%) to (35.8%) at the end of the study.