Aims of the study: An assessment of the incidence and severity of suicidal thoughts and depression in a group of patients with lung cancer. Furthermore, we have investigated whether the increase in suicidal thoughts and depression depends on pain intensity and the overall physical function of patients. Material and methods: The study included 62 patients diagnosed with lung cancer, hospitalised in the Department of Thoracic Surgery at the Thoracic Surgery Clinic in Lublin, at the Independent Public Clinical Hospital No. 4 in Lublin. The patient population included 21 females (34%) and 41 males (66%). A total of 35 (56%) respondents came from rural regions, and the remaining 27 (44%) from the city. The average age was 59 years (standard deviation was 12.6). The severity of depression and suicidal thoughts was evaluated using the Beck Depression Inventory. In addition, Numeric Pain Intensity Scale and the Karnofsky Scale were used to assess the general functioning of the study population. Sociodemographic variables were analysed using a self-designed survey. Results: Suicidal thoughts occurred in 6.45% of respondents, exclusively in males. Statistical analysis showed that the group with depression received significantly less points in a scale measuring general functioning. There was a negative correlation between depression severity and the general functioning of patients. Depression was diagnosed in 32.25% of respondents, including mild in 25.8%, moderate in 6.45%, and severe in 4.83%. Depression affected 36.58% of men and 23.8% of women. No correlation between the severity of depression and the severity of pain was observed. Conclusions: The severity of depression increases with the decrease in overall physical functioning and is not related to pain severity.