The objective of this work was to recognise the most frequent problems regarding biopsychosocial functioning of patients suffering from colorectal cancer and undergoing chemotherapy. The study used the method of diagnostic survey and a survey questionnaire developed by the authors was a measurement tool. The study population included 30 patients receiving 5-Fluorouracil with leucovorine chemotherapy. Respondents aged between 60 and 69 years comprised the biggest age subgroup (30%) followed by patients between 70 and 79 years old (27%). Conclusions. Evaluation of biopsychosocial functioning was the basis for the recognition of problems experienced by patients undergoing chemotherapy. The most frequent problems included: nausea, insomnia, fatigue, tiredness, and decreased appetite. Anxiety was observed among the majority of respondents, however at the same time these patients were optimistic about their future. Patient’s mood during chemotherapy depended significantly on the way the therapy affected one’s activity in everyday life. Most respondents were convinced their level of knowledge regarding chemotherapy was sufficient.