The incremental net benefit (INB) and the related acceptability curves for public health programs provide valuable tools for decision making. We proposed to apply them to the assessment of mass screening of colorectal cancer. The now standard guaiac fecal occult blood test (FOBT) is already implemented in several countries. We considered the innovative immunological FOBT and computed tomography colonography (CTC) as competing screening technologies. Using biennial guaiac FOBT as the reference strategy, we estimated the cost-effectiveness of the following alternatives: biennial immunological FOBT, CTC every 5 years (strategy CTC5), and CTC every 10 years (strategy CTC10). Over a 30-year horizon and from the perspective of a third-party payer, we developed a Markov model on a hypothetical cohort of 100,000 subjects at average risk of colorectal cancer. Close expected net benefits between immunological FOBT and CTC5 induced uncertainty in the choice of the optimal strategy. Probabilistic sensibility analysis then suggested that below a willingness to pay (WTP) per life-years gained (LYG) of 8,587 €/LYG, CTC10 was optimal, while CTC5 would be preferred beyond a WTP of 8,587 €/LYG.