Several versions of Diogenes of Sinope’s death are reported in Book VI of the Lives and Opinions of Eminent Philosophers. The heirs of Diogenes have transmitted to posterity that of suicide by self-asphyxiation, a death they deem worthy of his philosophy. This study aims to identify the Cynic foundation of Diogenes’ suicide by reconstructing the Cynic outlook on voluntary death. Several fragments and testimonies show that the Cynics consider life and death indifferent: what matters above all is to lead a (...) good life. Suicide is only justified when the philosopher’s body suffers from extreme and lasting weakness. To reach and maintain his ideal of freedom, the Cynic must submit his body to a training that requires some physical strength. Therefore, as soon as he loses the capacity to practise the Cynic askesis because of the physical limitations brought on by old age or illness, the philosopher does not hesitate commit suicide. This justification is attested in the exhortations to suicide formulated by the Cynics and in the accounts of the self-inflicted deaths of Metrocles, Heracles, Demonax and Peregrinus. (shrink)