The uptake of the immunochemical faecal occult blood test (iFOBT) in many countries with an opportunistic colorectal cancer (CRC) screening programme remains suboptimal. This study aimed to determine the rate, associated factors and reasons of refusal to perform the iFOBT test offered under an opportunistic CRC screening programme in semi-urban communities. This cross-sectional study was conducted among the average-risk individuals living in semi-urban areas, who sought care from public primary care centres across Kedah state, Malaysia. The information regarding the sociodemographic and clinical characteristics of individuals who were offered the iFOBT between January and April 2019, along with their willingness to perform the test, was gathered. The factors associated with the refusal were further explored using the logistic regression analysis. The individuals offered the iFOBT (n = 920) were mainly female (52.4%) and had a mean age of 58.7±10.6 years. The refusal rate of the iFOBT was 32.2%. Patients who did not have hypertension (adjusted OR: 3.33; 95% CI: 2.44, 4.54), did not have CRC symptoms (adjusted OR: 3.15; 95% CI:1.26, 7.89), had the test offered by either medical assistants (adjusted OR: 2.44; 95% CI: 1.71, 3.49) or nurses (adjusted OR: 2.41; 95% CI 1.65, 3.51), did not have diabetes (adjusted OR: 1.99; 95% CI: 1.42, 2.77),and were not active smokers (adjusted OR: 1.74; 95% CI: 1.22, 2.47), were more likely to refuse the iFOBT. The common reasons of refusing the test included "feeling not ready for the test" (21.6%) and "feeling healthy" (14.9%). The iFOBT was refused by one-third of the average-risk individuals from semi-urban communities. The associated factors and reasons of refusal found in this study could guide policymakers in developing targeted interventions to boost the uptake of CRC screening in Malaysia.