A grounded theory approach was used to generate theory about clients' perceptions of polysomnography, and the relationships between these perceptions and compliance with therapy. Interviews were conducted with two groups of clients: those who complied with recommended therapy (Continuous Positive Airways Pressure) and those who did not. Compliance with suggested therapy appeared to be related to the degree of benefit derived by the client. In addition, there were problems with the process of diagnosis and follow-up that impacted on client satisfaction and may have influenced their compliance. These findings have highlighted issues which have been used to generate theories that will be tested in future research.