The aim of the present study was (a) to investigate the relative efficacy of autogenic training and future oriented hypnotic imagery in the treatment of tension headache and (b) to explore the extent to which therapy factors such as relaxation, imagery skills, and hypnotizability mediate therapy outcome. Patients were randomly assigned to the 2 therapy conditions and therapists. 55 patients (28 in the autogenic therapy condition and 27 in the future oriented hypnotic imagery condition) completed the 4 therapy sessions and 2 assessment sessions. No significant main effect or interaction effects for treatment condition or therapist was revealed. A significant effect for time in analyzing scores for headache pain, pain medication usage, depression, and state anxiety was found. In the self-hypnosis condition, pain reduction proved to be associated with depth of relaxation during home practice (as assessed with diaries) and capacity to involve in imagery (as assessed with the Dutch version [van der Velden & Spinhoven, 1984] of the Creative Imagination Scale [Barber & Wilson, 1978/79; Wilson & Barber, 1978]). After statistically controlling for relaxation and imagery, hypnotizability scores (as assessed with the Dutch version [Oyen & Spinhoven, 1983] of the Stanford Hypnotic Clinical Scale [Morgan & J.R. Hilgard, 1975, 1978/79]) were significantly correlated with ratings of pain reduction. Results are discussed in the context of the neo-dissociation and social-cognitive model of hypnoanalgesia. The clinical relevance and the methodological shortcomings of the present study are also critically assessed.