SUMMARY Primary laboratory experiments were carried out to reveal the immunogenic effect of a locally already produced Gumboro disease vaccine prepared from the imported attenuated (Burse Vac M) strain, on chicks either previously vaccinated with some live Newcastle disease vaccines or not. These primary laboratory experiments that the usedGumboro disease vaccine gave high protection percentage against Guboro disease as shown out after challenge test, also it was shown that this vaccine has no
immunosuppressive effect on the birds vaccinated by Newcastle disease live vaccine. This was indicated the rise of the immunity level in the birds previously vaccinated against Newcastle disease. After obtaining these primary laboratory results; 10.000 chicks in different private broiler farms were vaccinated with the mentioned Gumboro disease vaccine after being vaccinated with Newcastle disease vaccines according to the special vaccination programms of each farm. The results obtained from the laboratory experiments were identical with those obtained from the field ones. It was concluded that the locally prepared Gumboro disease vaccine (Bursa Vac. M) strain was safe and effecient in protecting the vaccinated birds against Gumboro disease; also it was proved that this vaccine has no immunosuppressive effect on chicks previously vaccinated with live Newcastle disease vaccines.