Background: The National Bowel Cancer Screening Program (NBCSP) is a population-based screening program based on a mailed screening invitation and immunochemical faecal occult blood test. Initial published evidence from the NBCSP concurs with international evidence on similar colorectal cancer screening programs about the unequal participation by different population sub-groups. The aim of the paper is to present a cross-sectional analysis of participation in the NBCSP for Adelaide, in order to identify geographical areas and population groups which may benefit from targeted approaches to increase participation rates in colorectal cancer screening. Method: De-identified data from the NBCSP (February 2007 to July 2008) were provided by Medicare Australia. Mapping and analysis of the NBCSP data was performed using ESRI ArcGIS software, MapInfo, Microsoft Access and Microsoft Excel. Data was aggregated to postcode and participation was then mapped according to overall participation rates, sex and age. Results: The overall participation rate was 46.9%, although this differed by age, gender and geographical location. Maps provided in the paper reveal a socio-economic patterning of participation in the NBCSP, whereby areas with higher participation rates are also more affluent, whereas areas with lower participation rates tend to be more disadvantaged. Conclusion: Findings from this study suggest inequities in participation in the NBCSP on the basis of gender, geographical location, and socio-economic status.