Addiction to drugs is a widely acknowledged problem in South Africa. Newer developments in the study of addiction include behaviours such as gambling and sex as part of a broader syndrome. International research has established that most people with one addiction are at risk for co-occurring addictions which are frequently undiagnosed and untreated. Multiple addictions (MA) have been shown to combine in specific patterns to produce addiction interaction disorder (AID) resulting in a more complex, treatment- resistant illness. This was the first study South Africa to investigate if people with substance use disorders had other addictions. The research had three aims: to establish if in-patients admitted to three drug rehabilitation centres had other addictions, to investigate the extent of the MA and AID and to determine whether the treatment programmes managed them appropriately. The study employed the mixed methods research design and was located at three in-patient facilities in Durban, KwaZulu-Natal. During the first phase, discussion groups were held with professionals that explored their perceptions of MA, AID and current treatment programmes. The second phase involved a survey of 123 participants screened for poly-substance abuse, sex (including internet) addiction and problem gambling. The third phase utilised in-depth interviews with 25 participants displaying MA to understand the development of addiction, AID and treatment received. The data were analysed utilising descriptive and statistical analysis for the survey data, and thematic analysis for the in-depth interviews and discussion groups. The study found a high incidence of MA within the survey population of 54%; 37% of participants tested positive or at risk for problem gambling and 41% tested positive for sex addiction with 24% of the participants being positive for both. In-depth interviews revealed high rates of trauma, especially for the female participants and demonstrated the complex interrelationship between addictions. AID was identified in all 25 participants. In KwaZulu- Natal, it appears that MA and AID are currently not being assessed or treated. The study highlights the need for a broader conceptualisation of addiction which would improve current assessment and treatment and has implications for further training of professionals and addiction policy in South Africa. / Ph.D. University of KwaZulu-Natal, Durban 2013.