Due to the increasing importance of electronic services (e-services) in the service economy, and due to the increased reliance on such services, we propose a quantitative assessment of the level of trustworthiness of an e-service provider organization. A typical service organization provides services to its service users, such as e-learning, e-health, e-commerce or e-banking services, among others. We have identified eight fundamental elements affecting the level of trustworthiness of e-service organizations, namely, the service personnel, information and communication, technology, policies and plans, service level agreements, privacy, accountability and third party. The proposed assessment tool covers these fundamental elements and consists of two questionnaires used to assess the trustworthiness. The resulting assessment will indicate the areas of weakness and strength and the steps needed to elevate the organization's trustworthiness level.