Life-threatening diseases such as cancer can create hopelessness and loneliness by altering the lifestyle of the patient and family. Perceived social support may facilitate coping with illness. The aim of this study was to investigate the relationship between hopelessness, loneliness, and perceived social support from family in Turkish patients with cancer. This study involved 188 patients with cancer. The data were collected using a questionnaire that determined the sociodemographic features, the Beck Hopelessness Scale, the UCLA Loneliness Scale, and Perceived Social Support from Family Scale. Data were evaluated with Mann-Whitney U and Kruskall-Wallis and Spearman product moment correlation coefficients. The mean scores of hopelessness (0-20), loneliness (20-80), and perceived social support from family (0-20) were 6.8 +/- 0.4, 35.8 +/- 0.8, and 15.2 +/- 0.2, respectively. A statistically positive relationship existed between hopelessness and loneliness. A negative relationship between loneliness, hopelessness, and perceived social support from family was found (p < 0.05). Cancer patients who had family history of cancer and long disease duration had low social support from family. The hopelessness score was significantly higher in female, older, illiterate, and village-dwelling cancer patients. In cases where the perceived social support levels were determined to be high; the cancer patients were not hopeless or lonely. We found that decreased social support was associated with increased loneliness and hopelessness. The present evaluation indicates that although the levels of perceived social support of patients from their families may be sufficient to prevent loneliness or hopelessness, these parameters need to be evaluated periodically to maintain the patients' well-being.