OBJECTIVES: Many studies of cancer worry use items measuring frequency or intensity. Little is known about how each of these relate to cancer screening uptake. This study compared the association between worry frequency vs. intensity and colorectal cancer screening intention/uptake. METHODS: Across four surveys (2014-2016), we collected data from 2878 screening-eligible men and women (aged 60-70) in England. Measures included single-items assessing cancer worry frequency and intensity, and a derived combination of both. We also assessed self-reported past faecal occult blood testing uptake (ever vs. never), intention to participate when next invited (yes vs. no), and demographics. Using logistic regression, we compared a model containing sociodemographic characteristics (Model 1), with four models adding cancer worry frequency (Model 2), intensity (Model 3), both (Model 4), or the combined measure (Model 5). RESULTS: A model with cancer worry intensity and demographics (Model 3) explained significantly more variance in uptake and intention ( R2 = 0.068 and 0.062, respectively) than demographics alone (Model 1: R2 = 0.058 and 0.042; p < 0.001), or a model with demographics and cancer worry frequency (Model 2: R2 = 0.059 and 0.052; p < 0.001). The model was also equally as effective as models including both the frequency and intensity items (Model 4: R2 = 0.070 n.s. and 0.062 n.s.), or using the derived combination of both (Model 5: R2 = 0.063 n.s. and 0.053 n.s.). CONCLUSION: A single item measure of cancer worry intensity appeared to be most parsimonious for explaining variance in colorectal cancer screening intention and uptake.