The success of a population-based screening for colorectal cancer (CRC) is determined to a large extent by general practitioner (GP) attitudes, beliefs and support. The extent to which GPs support population-based CRC screening remains unclear. To assess the knowledge, attitudes and practices of GPs in relation to CRC screening, and to identify the determinants of GP support for population-based faecal-occult blood testing (FOBT). A cross-sectional postal survey was conducted with a random sample of 692 GPs in Queensland, -Australia. We assessed GP knowledge, attitudes and practices concerning CRC screening in relation to their stance on population-based FOBT screening. Although the response rate was low (41%), participants were representative of Queensland GPs in general. Of 284 participating GPs, 143 (50.5%) indicated that they would support a population-based FOBT screening programme, 42 (14.8%) would not and 98 (34.6%) were unsure. Belief in FOBT test efficacy (P <0.001), possession of CRC guidelines (P <0.05) and belief in earlier stage detection (P <0.05) were major determinants of support for population-based FOBT screening. No significant association was observed for doctor's sex, location of practice, age, year completed medical training, membership of a Division of General Practice, number of weekly consultations, number of patients investigated for CRC per month, size of practice, own family history of CRC, interest in further information on CRC screening or treatment, and current use of FOBT with asymptomatic patients aged > or =40 years. GP support for FOBT population-based screening appears to have increased over recent years. The knowledge and attitudes/beliefs of GPs are key determinants of their support.