Ethics are moral principles that direct or influence peoples’ attitude and conduct. It also has an incontrovertible impact on legitimacy and value standard of any profession. However, there has been lots of questions raised on low level of ethical standard among Quantity Surveyors in Nigeria. Due to the development, this study aims to identify and analyze factors contributing to unethical conduct among Quantity Surveyors in the construction industry. Well-structured questionnaire covering the various factors contributing to unethical behavior by Quantity Surveyors were administered to the construction professionals. 228 legitimate reactions were retrieved and analyzed using Mean Item Score (MIS) and Factor Analysis (FA) respectively. It was revealed from the study that excessive love for money (greed), salaries of workers are delay and economic downturn were the top three factors contributing to unethical conduct by Quantity Surveyors in the construction industry. Furthermore, Factor Analysis was employed in reducing these factors to six major contributing factors. Thus, the study recommended that there should be total enforcement of the code of conduct on Quantity Surveyors by the professional bodies. Results from this study give adequate confirmation and helpful pointers in clarifying some misinterpretations about factors contributing to unethical conduct by Quantity Surveyors in the construction industry and possible solution.