In a nation-wide investigation, covering all the hearing centres in Sweden, a study was made of adaptation processes, subjective discomfort from tinnitus, subjective loudness of tinnitus and psychological complaints in 3372 subjects by means of a questionnaire. The most important predictors of discomfort from and adaptation to tinnitus were found to be the controllability and the degree of maskability by external sounds, i.e. the subject's coping abilities or internal-external locus of control. Increased control and masking effects from the environment imply a decrease in discomfort and better adaptation. The most important predictor of worsened subjective loudness of tinnitus was the duration of the tinnitus. That is, subjects who had had tinnitus for a longer time perceived the loudness as more intense. The psychosomatic factors which most strongly predicted increased discomfort from and decreased tolerance to tinnitus were depression and insomnia. These findings have theoretical and practical implications for the management and treatment of tinnitus.