Screening is seen by many as a key element in cancer control strategies. Differences in uptake of screening related to socio-economic status exist and may contribute to differences in morbidity and mortality across socio-economic groups. Although a number of factors are likely to underlie differential uptake, differential access to subsequent diagnostic tests and/or treatment may have a pivotal role. This study examines differences in the uptake of cancer screening in Ireland related to socio-economic status. Data were extracted from SLÁN 2007 concerning uptake of breast, cervical, colorectal and prostate cancer screening in the preceding 12 months. Concentration indices were calculated and decomposed. Particular emphasis was placed in the decomposition upon the impact of private health insurance, evidenced in other work to impact on access to care within the mixed public–private Irish health system. This study found that significant differences related to socio-economic status exist with respect to uptake of cancer screening and that the main determinant of difference for breast, colorectal and prostate cancer screening was possession of private insurance. This may have profound implications for the design of cancer control strategies in countries where private insurance has a significant role, even where screening services are publicly funded and population based. Copyright © 2011 John Wiley & Sons, Ltd.