Creativity has become a topic of ever-increasing interest in educational settings where principals are responsible for improving schools. In Iran, there is a need for research on evaluating the creativity of school principals due to the importance of their role in improving schools. In this paper we aim to assess the creativity of school principals in schools of Iran and investigate its relationship with their job performance and relations with students and teachers. The effect of age and educational level factors on their creativity were also studied. This is a case study conducted in boys' middle schools of Urmia city located in West Azerbaijan Province of Iran. Participants included 52 schools principals aged between 34-54 years working in the academic year 2012-2013 who were randomly selected using Krejcie and Morgan table. Their creativity (CR), job performance (JP), and human relations (HR) were measured using designed Persianlanguage questionnaires. Collected data were analyzed using statistical tests (mean and standard deviation) and three formulated research hypotheses were tested by applying Pearson's correlation coefficient and one-way ANOVA in SPSS software. Their scores showed that they had a relatively good level of CR, HR and JP. Results of statistical analysis revealed that there was no significant relationship between Iranian school principals' creativity and human relations, but their creativity was significantly related to their job performance. Also, it was found that age and educational level had no significant effect on their creativity.