Objective: Tourette syndrome is often associated with attention deficit hyperactivity disorder, obsessive compulsive disorder and other co-morbidities, the presence of which can reduce health-related quality of life. The relationship between the number and type of co-morbidities and tic severity upon health-related quality of life has been insufficiently examined in Tourette syndrome populations and not at all in the Australian context. We hypothesised that an increased number of co-morbid diagnoses would be inversely related to health-related quality of life and that the presence of attention deficit hyperactivity disorder and obsessive compulsive disorder in particular would negatively impact health-related quality of life. Method: In all, 83 people with a previously established diagnosis of Tourette syndrome, who responded to a letter of invitation sent to the Tourette Syndrome Association of Australia past-member database, formed the study sample. Participants completed the Gilles de la Tourette Syndrome-Quality of Life Scale and a short form of the National Hospital Interview Schedule to assess tics and related behaviours. Results: Participants with pure-Tourette syndrome had significantly better health-related quality of life than those with Tourette syndrome and three or more co-morbid diagnoses. Few differences were observed between the pure-Tourette syndrome and Tourette syndrome and one or two co-morbid diagnoses groups. Analysis of the impact of individual co-morbid disorders and Tourette syndrome symptoms on health-related quality of life indicated that attention deficit hyperactivity disorder exerted a significant negative effect, as did the presence of complex tics, especially coprolalia and copropraxia. When these variables were examined in multiple regression analysis, number of co-morbidities and the presence of coprophenomena emerged as significant predictors of health-related quality of life. Conclusion: While tics are the defining feature of Tourette syndrome, it appears to be the presence of co-morbidities, attention deficit hyperactivity disorder, in particular, and coprophenomena that have the greater impact on health-related quality of life. This has implications for symptom-targeting in the treatment of Tourette syndrome since all available treatments are symptomatic and not disease modifying.