Introduction: Today, the extent of nursing roles increases the need to continuing education and review of nursing functions and competencies. DACUM approach is a method that all of duties and tasks of a specific job assessed and then all of activities in those duties for educational needs focused.

 Aim: The aim of this study was to identify the main and sub-main tasks of nursing job to determine necessary nurses' competencies to perform these tasks and their educational needs in those competencies' in Tehran central hospital affiliated Oil Company.

Method: This study was carried out in two stages using by DACUM method. In the first stage, 12 qualified and experienced nurses in the hospital were selected purposefully and participated in the DACUM initial workshop. After describing and explaining the aims of workshop and the DACUM process, the participants with agreement of all members identified the main and sub-main tasks and assignments of nursing job. Then, based on extracted task and activities a questionnaire containing with (59) questions based on the three components of knowledge, attitude and skill was designed in two dimensions of current situation and the desirable situation that (127) nurses completed it. This sample size had been determined using Cochran's sampling formula and they were randomly selected answered the questionnaire, in the second stage. The content validity and Cronbach's alpha was computed for its reliability. Data analysis was done using dependent two-sample T2 test..

Results: The results showed that all of the nurses at hospital require training in all their job task and duties. Based on these results and considering the mean difference between the status quo and the desirable situation, in knowledge competencies "the knowledge about planning and organizing principles for achieving greater productivity" with a mean of (2.02), at skill competencies " management of cost - benefit, assessment and choosing the best solution with different timing horizon" as well as "monitoring and measuring the performance of oneself, others or the organization for improvement or corrective action" with a mean difference of (1.25), and in attitude competencies, " high motivation in order to provide better services" with a mean difference of (0.67) are considered as the most important educational needs of the nurses.

Conclusions: From these findings can be used to develop training courses for nurses in this hospital and other hospital that similar with it. Also, the educational need assessment method (DACUM) that presented in this study can be used for educational need assessment of other organizational levels in the hospital and other health care organization