This essay will discuss Ernest Hemingway's Islands in the Stream, posthumously published 1970, focusing in particular on the importance of the protagonist's fluid gender identity and interest in queer sexuality. Central to my discussion is queer theorist Judith Butler's view of gender as something performed and contextual and her objection to the binary of man and woman. I will argue that the issues of gender identity and queer forms of sexuality are ever-present throughout the novel, and that in the protagonist Thomas Hudson, Hemingway presents a different hero in comparison to the hardboiled macho-man he has been claimed to glorify in his work. My thesis is that the protagonist's denial of his ambiguous gender identity and his interest in queer sexualitey are the underlying causes for the development of the plot. The novel will be discussed in relation to the thesis in chronological order: first, it examines the protagonist's detachment and separation from his sons; second, his difficulties to sustain any longer relationships with women, and third, why he never dares to trust the people who say they love him.