We interviewed 20 patients staying at a hospital unit, by means of a data collection instrument that is based on the eclectic model, with a view to characterizing the biological, psychological and sociocultural aspects involving human sexuality which are affected in patients with onco-hematological diseases. The research complied with ethical requirements for studies involving human beings. The results revealed that these clients presented problems related to biological aspects, mainly with respect to the phase of sexual desire (60% of the sample), sexual excitation (75%) and orgasm (75%). The psychological aspects related to sexual self-image were affected in 60% of the sample; problems related to social aspects (85%) were mainly due to the fear of acquiring an infection as a result of the low immunity provoked by the disease and treatment. These clients demonstrated alterations in their sexual function and in the way they expressed their sexuality.