The aim of this trial is to determine effect of homeopathy on menstrual pain severity, menstrual symptoms and quality of life of students with primary dysmenorrhoea. 80 eligible students living in dormitories of Tabriz University of Medical Sciences will be recruited after getting written informed consent. Students will be asked to fill in a form including reports of menstrual pain and symptom severity during four consecutive cycles (two pre- and two post- intervention cycles) and give them to the researcher in every visit. In the second visit, in day of 6-10 of the second menstrual cycle, the researcher will select 60 students from the persons who have filled in the forms carefully and will ask them to complete the SF-36 questionnaire at that time and go to the homoeopath physician in the next 3 days. The physician (with 6 years experience in homeopathy) will visit the participants twice with one month interval and in each visit will give a homeopathic medicine, unique for each participant, to the research assistant. The assistant will give every participant either the prescribed homeopathic remedy (soluble in water) or only water (placebo), according to allocation sequence and will ask them to take it under her supervision. Block randomization with block sizes 4 and 6 using a computerized program will be used to determine allocation sequence. Sequentially numbered opaque sealed envelopes will be used for allocation concealment which will be opened by the resistant at the moment of giving medicine\placebo to each participant. At the end visit (about one month after the second prescription), the participants will fill in the SF-36 questionnaire again.