The present study attempts to reconstruct Husserl's account of empirical illusion and hallucination and disclose the significance of sense-deception in Husserl's phenomenology. By clarifying the relation between the "leibhaftige presence" and "existence" of perceived objects, I shall be able to contend that illusion and hallucination are nullified, invalid perceptions. Non-existence or in-actuality is a form of invalidity: the Ungültigkeit of what demands its insertion in the totality of actual existence. Husserl elaborates an ex-negativo account of in-actuality, in which sensory deception refers to a modal modification, which is always relative and contextual in relation to the total nexus of experience in its intersubjectively validated and harmonious unfolding.