Aim of the study: The aim of the study was to assess the psychological functioning of women and men diagnosed with cancer. Material and methods: The study involved 572 patients of Oncology Centre in Warsaw, 19-69 years, diagnosed with cancer: reproductive system (26.3%), head and neck (12.5%), gastrointestinal tract (12.1%), breast (10.7%), urologic (9.8%), and nervous tissue (7%), lung (7%), lymphomas (6.7%), other (7.9%). Among the respondents are women (60%), people with secondary education (39%), living in a big city (47.8%), remaining in relationships (75.9%). The following questionnaires were used: Generalized Self Efficacy Scale, Cognitive Emotion Regulation Questionnaire, Mental Adjustment to Cancer Scale (Mini-MAC), Hospital Anxiety and Depression Scale and questionnaire on demographic variables. Group of men and women were compared in terms of the variables tested using Student's t test for independent samples. Results: Women, compared to men: have a lower sense of self-efficiency, are more likely to use strategies to cope with stress, such as rumination, catastrophizing, and blaming others, can be characterized by having the following attitudes toward disease: high preoccupation with anxiety, high helplessness-hopelessness, high fighting spirit, and high positive re-evaluation, have a higher severity of anxiety and depression. Conclusions: Psychological interventions to support the process of cancer treatment should take into account the specificity of the psychological functioning of men and women, and should be tailored to their needs.