 Since his youth, Mårtensson wrote mainly science fiction short stories and novels, and a lengthy fantasy work in three volumes published in 1979–83 and in a revised edition in 1997.His work has in style and themes been compared by Swedish critics to those of Clifford D. Simak, Theodore Sturgeon, Arabian Nights and J. R. R. Tolkien.The Scandinavian flavour has also been emphasized.