The aim of this study was to investigate the direction of the administrative decision making process of school principals considering professional ethics through some situations related to teaching staff and to students in basic schools in Muscat governarate in Sultanate of Oman. It aimed also to get mechanisms suggested by the sample of this study to contribute in guiding school principals to make their decisions in the light of professional ethics. A descriptive methodology was used. Data was collected by interviews of 20 schools' principals from basic education schools of the cycle two in Muscat Governorate. The collected data was dealt using qualitative approach through analyzing the responses and their frequencies. This study resulted in important findings, according to the key correction made in this study, the most frequent ethical theories included in ethics practiced by school principals in dealing with the situations of the current study related to teaching staff were the theory of criticism and the care theory. In the situations related to students, the most frequent theories were the Islamic and the deontology theories. Findings also showed that some situations were not complicated, so principals dealt with them from a single sided perspective in decision making. Whereas more complicated situations required using more than one theory to make decisions. The individuals of the sample have suggested several methods to develop the process of administrative decision making in view of professional ethics. The most important suggestions were to provide training courses in ethics, sharing experience through exchange visits among principals and encouraging awareness about ethics. In addition, they suggested that the manual of principals should be developed. They also advised principals not to rush and to be moderate in decision making. The study ended up with some recommendations and research proposals.