Cancer is the second leading cause of death in developed countries and the third one in developing countries. The aim of this study was to determine the knowledge on colorectal cancer and the related background factors in the urban population aged over 50 years in the western of Iran. This study was of descriptive cross-sectional type which was conducted among 500 individuals aged over 50 years in city Ravansar were randomly selected to participate voluntarily in the study. Data collected by questioner and were analyzed by SPSS version 21 using independent t-test, ANOVA and correlation statistical tests at 95% significant level. The mean age of respondents was 58.32 years [95% CI: 57.7, 58.9], ranged from 50 to 73 years. Only 4.7 percent of the participants knew what colorectal cancer was and what its screening methods were. The mean score of knowledge construct about colorectal cancer among the participants was 5.72 with standard deviation of ±2.57. Furthermore, knowledge of cervical cancer was significant association with sex, educational level and positive family history of colorectal cancer. In addition, knowledge about colorectal cancer was significantly related to the age (r= -0. 095 & P=0.040). Based on our result, it seems that designing and implementation of educational programs to improve knowledge about colorectal cancer among population is necessary.