[Truncated abstract] Background: A review of the literature indicated there was a need for more long-term randomised controlled studies on the effects of BRCA counselling/testing on high risk women, including improved strategies for risk communication. Reviews have also shown women are confused about the significance of inconclusive or non informative results with a need for more research in this area. Aims: The general aim of this study was to evaluate the impact of breast cancer genetic counselling on psychological distress levels, perception of risk, genetic knowledge and understanding of BRCA testing/test results in a cohort of 207 women from high risk breast cancer families who were referred for genetic counselling in Perth during the period 1997 to 2001. Short- and long-term impact of BRCA genetic counselling/testing was determined in women with and without cancer in a randomised controlled trial as part of which women were randomised to either receive immediate versus delayed genetic counselling. This included family communication patterns before BRCA testing, anticipated outcomes of testing on oneself and family including intentions for result disclosure. Comprehension of index and predictive BRCA testing with possible results was assessed both in the short- and the long-term and understanding of individual or family BRCA test results was evaluated at long-term. The effect of genetic counselling on breast cancer risk perception in unaffected women was evaluated. This study considered a theoretical framework of educational learning theories to provide a basis for risk communication with possible relevance for future research. ... Only 25% of the original study population (52/207) reported BRCA results and women's understanding of results is concerning. Key findings were: 1. The majority of affected women received an inconclusive result. 2. Out of twelve unaffected women who reported results, seven were inconclusive which are not congruent with predictive testing. This implies that these women did not understand their test result. 3. A minority of untested relatives did not know whether a family mutation had or had not been found in their tested family member or what their actual test result was. This implies either a lack of disclosure or that woman did not understand the rationale for and significance of testing for a family mutation. 4. Three relatives did not understand a positive result was a mutation. Conclusion: The implication of this research for breast cancer counselling and testing services is that women who wait for counselling are no worse off in terms of short- or long-term general psychological distress than women who receive the intervention early. There is a suggestion that unaffected women without the disease found counselling more advantageous than affected women. The meaning of BRCA results as reported by women is concerning particularly women's understanding of negative and inconclusive results and further research is needed in this area. Too much information presented at counselling may affect women's comprehension of risk, BRCA testing and future test results and further research is required to evaluate the effects of information overload.