The aim of the study was to examine how social workers investigate and assess addiction cases whether gender matters or not. The following questions were asked in the study; • Does the gender of the client influence whether a case is opened after the first meeting at the Addiction Unit? • Do social workers consider there is a difference in handling an addiction treatment investigation when the client is a man or a woman? • Do divergences exist in the assessment and the final decision process when the case concerns a man or a woman? The study is based on the qualitative method. The material is gathered from semi-structured interviews with social workers. Their job tasks include assessment and evaluation of addiction cases. The empiric interview material has been analyzed from a gender perspective. The results show that the social workers unanimously agree; the gender does not affect the investigation, assessment and whether a case is opened or not when a client asks for addiction treatment. The social workers almost agree; it is primarily the client’s point of view and treatment needs that decide the focus in the investigation, assessment and decision. However, gender may influence the selection of available treatments for the individual client. According to two social workers gender may influence reception, how the social workers at the Units talk about their clients, the severity and need.