Background N-of-1 trials are within-patient, randomised, double-blind, placebo-controlled cross-over comparisons of two drugs for chronic illnesses. We have investigated the use of these, offered to doctors as individualised medication effectiveness tests (IMETs), as a tool to improve drug prescribing. Aim To examine patient perspectives and experiences of n-of-1 trials. Design of study We provided n-of-1 trials for osteoarthritis (OA), comparing paracetamol and ibuprofen; and attention deficit hyperactivity disorder (ADHD), comparing dexamphetamine or methylphenidate and placebo. Patients or their carers were surveyed before and after the trials by questionnaire, and after the trial by semi-structured interview with thematic analysis. Setting Australian community-based patients and practitioners. Method Forty-two patients with OA and 21 carers of patients with ADHD, for whom the effectiveness of proposed or existing medication was uncertain, completed the questionnaires, and 25 patients/carers (11 with OA and 14 with ADHD) participated in semi-structured interviews. Results Patients in this purposive sample were generally very satisfied with the n-of-1 trial process. Their participation led to increased knowledge, awareness and understanding of their condition, their bodies' response to it, and its management. Some of this arose specifically from use of daily symptom diaries. This led to a sense of empowerment and control as well as improved individually-focused care. Conclusions N-of-1 trials appeared to empower these patients as a result of both collecting information about their responses to different treatment options, and participating actively in subsequent therapeutic decisions. They are a patient-centred intervention that may improve medication management in suitable chronic diseases.