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The present work was conducted to study “ Interaction between wheat gall nematode Anguina tritici and wheat yellow ear rot Rathayibacter tritici “. Experiments included inoculation of wheat seeds (cv. Qods) with bacteria without nematode and inoculation with nematode. Experiments showed that the wheat yellow ear rot disease did not develop without the involvement of nematode. These experiments also revealed that the causal agent of wheat yellow ear rot could not penetrate seeds through either wounds or inflorescence. It only penetrated through nematode. The presence of nematode was necessary for reproduction of bacterium. If bacteria been injected into seeds without nematode, the disease of wheat yellow ear rot would not develop. The nematode could receive bacteria from either soil or bacterial- infested galls. Attachment of bacterium to nematode cuticle induced wound in the site of attachment. Therefore attachment of a large number of bacteria to nematode would induce nematode weakness as well as mortality.