Abstract: An attenuated infectious laryngotracheitis virus (ILT) that has the antigenic and virulence characteristics of ECACC at Accession No. V89042602, produces an average pock diameter on chorio-allantoic membrane of commercial eggs between 1.0 and 3. mm, exhibits substantially reduced virulence in comparison to ILT SA2 strain, and results in substantially less weight loss in poultry as compared to poultry infected with SA2. A method of producing this ILT virus by serially passaging ILT viral strain SA2 in primary cell cultures followed by serial passaging in embryonated eggs. A method for preventing infection by ILT virus in birds by administering a vaccine with an effective amount sufficient to elicit an immune response.