Introduction and objective: Cancer is a significant health and social issue. The diagnosis of cancer and the treatment process require changes in lifestyle and priorities. Both the patient and their family must adapt to new living conditions. The level of acceptance of the disease has a significant impact on the patient’s quality of life and plays an important role in the healing process. In connection with the above, a study was conducted to assess the importance of Type D personality in disease acceptance among patients with colorectal cancer. Materials and methods: A cross-sectional study was conducted among 200 patients with colorectal cancer. The study used the an original personality questionnaire, the Acceptance of Illness Scale, and the Type D Personality Scale. Statistical analysis included descriptive and analytical methods. The results of univariable analyses were verified using logistic regression. Results: The vast majority (75.5%) of participants with Type D personality did not accept their disease. Conclusions: The presence of Type D personality in patients with colorectal cancer in the period immediately preceding surgical intervention is associated with a lack of acceptance of the neoplastic disease. The significance of Type D personality is evident when considering the presence of colorectal cancer in the patient’s family in the context of acceptance of the disease.