By discussing transhumanism from a philosophical and phenomenological perspective, this paper examines one of the Trojan horses of transhumanist discourses: the desire for immortality. The well-known transhumanist Max More asserts: “We will no longer tolerate the tyranny of aging and death. Through genetic alterations, cellular manipulations, synthetic organs and any necessary means, we will endow ourselves with enduring vitality and remove our expiration date. We will each decide for ourselves how long we shall live” (More, 1999). Transhumanist movements usually request the right for human enhancement through technological objects and technical progress. Enhancement itself refers to a vast and very diverse set of activities. Even if the challenging topics of ageing and death are usually treated as psychological, social or political issues, transhumanist authors and associations envision how the human being could transcend his mortality through technological means, and how the trans-human could be immortal or amortal. This chapter first argues that transhumanist authors construe death as a biological issue, where death is no longer the evolutionary limit of living beings but rather an unnecessary disease which should be dealt with by technological breakthroughs. This hypothesis then raises the question of whether the transhumanist plea for immortality, by considering the human being as an object of natural, biological and medical sciences, amounts to a paradoxical application of automaton thinking to living beings. Indeed, by engaging with Martin Heidegger’s groundbreaking elucidation of Sein zum Tode (being-towards-death) in its Being and Time, this chapter shows how Heideggerian phenomenology depicts death not merely as a biological event befalling a Cartesian automaton but as an ontological structure of human existence. If, according to Heidegger, the prospect of death is an ontological disposition that opens us to our lived temporality, it is because Dasein is a being whose life takes historical form precisely because he is also defined by his finitude. This approach justifies a reversal of the Cartesian Cogito: from emergence (“therefore I am”, ergo sum), to finitude (“because I die”, sum moribundus), where “I am because I have the possibility of not being anymore”; or rather “I exist because I carry the possibility of non-existence.” From this perspective, this chapter develops an ontological reading of transhumanism, asking whether the achievement of immortality would abolish the original limit of our temporal horizon of existence. Consequently, this paper claims that to consider death as an external disease that might or might not happen to the human being is to reduce the human to a merely biological state, to his automatic animalitas; rather than seeing Dasein as a being fundamentally shaped by finitude. In this light, transhumanism can be read less as a scientific program than as representing the evolution of our technical imaginaries, as one that unveils a way in which we now conceive of our relation to ourselves and to finitude through technological mediation, whether in the form of rejuvenation, radical longevity, or even immortality.