Background: This study aimed to research the awareness of screening colonoscopy (SC) among patients with colorectal cancer (CRC) and their relatives. Methodology: A questionnaire form including information and behavior about colonoscopic screening for CRCs of patients and their first-degree relatives (FDRs) was prepared. Results: A total of 406 CRC patients were enrolled into the study, with 1534 FDRs (siblings n: 1381 and parents n: 153). Positive family history for CRC was found in 12% of the study population. Previous SC was performed in 11% of patients with CRC. Mean age of the patients whose FDRs underwent SC was lower than the patients whose FDRs did not (52 vs 57 years; p<0,001). The frequency of SC in FDRs was 64% in patients diagnosed CRC under 35 years of age. Persons having a positive family history of CRC had SC more often (51 vs 22%, p<0,001). FDRs of patients having a higher educational level and income had SC more frequently. Conclusions: When screening for CRC is planned, elderly subjects, those with family history for CRC, and those with low educational and lower income should be given esspecial attention in order that they be convinced to undergo screening for CRC.