This essay examines the ‘posthuman condition’ and its critical relevance to Joseph Conrad’s The Secret Agent (1907). It will be shown that oppressive examples of constitution-altering technologies find complex and recurrent depiction throughout the novel, often dismantling and redefining the physiques of their respective hosts. Most centrally however, it will be argued that Conrad criticises this notion of the posthuman condition through menacing depictions of ‘the Professor’, crucially emphasising the instability and endangerment potentially associated with the technologically-enhanced constitution. To this end, brief descriptions of The Secret Agent and contemporary conceptions of the posthuman condition will be provided. Thereafter, I shall explore the novel’s disquieting depictions of prosthetic technology and their detrimental effects upon the organic constitution, before then interrogating Conrad’s treatment of the posthuman condition and the devastation apparently inherent to this state of mechanical alteration. Finally, the novel’s ultimate denunciation of the posthuman condition will be considered, with particular reference to the death of Stevie and the numerous depictions of his fragmented body.