Disease concealment and disclosure one of the most complex challenges of thalassemia patients and it has a close relationship with stigma and leads to fear, anxiety, and negative reactions of others. The key of effective care and treatment of patients is to identify concealment experience resulted from illness-related stigma, disclosure and designing effective interventions. The present study aims to explore experience of thalassemia patients and their caregivers from illness concealment due to the stigma related to it and illness disclosure. This qualitative study done with content analysis approach, 21 participants were chosen by purposive sampling. The research was completed in medical center of Samen Alhojaj in Kerman in 2012-2014. Data were gathered by non-structural interviews using open questions and data were analyzed using qualitative content analysis with a conventional approach. The main category obtained in this study is living in darkness and lightness and it includes subcategories of A: concealment and B: disclosure feelings perceived by patients from thalassemia stigma suggest this fact that such patients not only involve with unpleasant mental and physical outcomes of the illness but also they face with illness concealment resulting from social stigma of the illness such that their physical and spiritual health is addressed. Therefore, concerning the results of this study, it is necessary to study illness concealment and disclosure and to formulate educational programs for all people in the society and relatives of the patient.