Several contemporary theories of ethics are reviewed and then linked to professional ethics. A questionnaire survey was conducted to collect primary data regarding quantity surveyors' attitudes towards professional ethics. The subjects were members of the Hong Kong Institute of Surveyors (HKIS). Systematic multivariate statistical analyses, such as ANOVA, F-distribution, and test for significance, were used to draw insight from the survey results. A discrepancy in the standards of professional ethics between senior and junior surveyors was found in the survey. In addition, wide and significant variances towards ethical concepts and decisionmaking considerations were found between senior and young practitioners. The results also show that the respondents attach great importance to the interest of their employers, their clients and themselves, which is not in line with the expectations of the general public. These findings provide useful information for researchers in studying specific ethical decision-making models as well as drafting more theoretically based rules of conduct.