Abstrac Not so long ago, the strength and power of an organization or a human community was its ability to access more material resources. In these current Competitive environment , situation completely has changed. The main Competitive advantage for organizations is their power to managing knowledge. the main capital of any product and service providing organizations is the knowledge they access. The major part of knowledge is tacit knowledge. Tacit knowledge is the main factor in organizations growth and their economical competitiveness and also there is positive relation between tacit knowledge and the organization’s efficiency and innovation. Therefore because of the important role of tacit knowledge in Success of organizations, continuous tacit knowledge assessment for determining level of organization’s tacit knowledge and defining strategies for boosting this kind of knowledge is very important. The purpose of this research is to offer a method for assessment of organizational tacit knowledge in order to determine how much every effective factor is in relation with organizational tacit knowledge field. For this purpose first by study available models and methods of assessment of organizational tacit knowledge and using definition of organizational tacit knowledge , effective factors on organizational tacit knowledge were determined . Three factors were determined as effective factors on organizational tacit knowledge : organizational culture , knowledge transfer channel and individual tacit knowledge. The effective variable on each factor were determine according to literature of this subject. And Then using Structual Equation Modeling Statistical analysis , created a method for assessment of organizational tacit knowledge .