Little is known about long-term effects of homeopathic treatment. Following a double-blind, placebo controlled trial of classical homeopathy in chronic headaches, we conducted a 1-year observational study of 18 patients following the double-blind phase, and a complete follow-up study of all trial participants. Eighteen patients received free treatment for daily diary data (frequency, intensity, duration of headaches) over the course of 1 y. All patients enrolled in the double-blind study were sent a 6-week headache diary, a follow-up questionnaire, a personality inventory and a complaint list. Eighty-seven, of the original 98 patients enrolled returned questionnaires, 81 returned diaries. There was no additional change from the end of the trial to the one-year follow-up. The improvement seen at the end of the 12-week trial was stable after 1 y. No differential effects according to treatment after the trial could be seen. Patients with no treatment following the trial had the most improvement after 1 y. Five of 18 patients can be counted responders according to ARIMA analysis of single-case time-series. Patients with double diagnoses and longer treatment duration tended to have clearer improvements than the rest of the patients. Approximately 30% of patients in homeopathic treatment will benefit after 1 y of treatment. There is no indication of a specific, or of a delayed effect of homeopathy.