Objective: To compare the uptake of faecal immunochemical occult blood test (FIT) with guaiac faecal occult blood test (gFOBT) in a screening programme, with specific attention to the demographic and socioeconomic factors that might affect test uptake. Setting: The Clalit Health Service screening programme, Israel. Methods: Average-risk individuals aged 50-75 years were randomized into a FITarm or gFOBTarm using a programme based on the socioeconomic status (SES) of their primary care clinics. G-FOBT was performed with Hemoccult SENSA ™ (3 evacuations) and FIT with the OC-MICRO™ (3 evacuations, refrigerating mandated). The GLIMMIX model was used. Results There were 5,464 and 10,668 eligible participants in the FIT and gFOBT arms respectively. Compliance in taking the kits was better (but not statistically significantly better) with gFOBT (37.8% vs. 29.3%; odds ratio [OR] 1.43 [95% CI 0.73-2.80]; P = 0.227). Kit return was higher in the FIT arm (65.0% vs. 78.9%; OR 0.45 [95% CI 0.24-0.83], P = 0.021). Overall test uptake was affected by age, gender, being immigrant and SES (determined by whether or not the participant paid national insurance tax, and the SES of the primary care clinic). The overall uptake of gFOBT and FIT was comparable (OR 0.996 [95% CI 0.46-2.17], P = 0.99). Conclusions: Overall compliance for test uptake was comparable between the two methods despite the more demanding procedure in the FIT arm. Sociodemographic parameters were the major determinants of compliance. An educational programme, with emphasis on the sociodemographic characteristics of the target population, should be instigated.