Background : Homeopathic Pathogenetic Trials (HPTs) are a pillar of homeopathy, a key source of the symptoms characteristic of a particular homeopathic medicine. Homeopaths choose homeopathic medicines by comparing these remedy pictures with the symptoms the patient is presenting. Thus, recognition of these symptom sets underpins the clinical practice of homeopathy.Objective : To test whether HPTs generate consistent and recognisable sets of symptoms in consecutive trials.Design : Practising homeopaths, blinded to the homeopathic medicine under investigation, were given the set of symptoms generated during an unpublished HPT and asked to identify the homeopathic medicine used.Homeopathic trial substance : Ozone, prepared by homeopathic method to the ultramolecular dilution of 30c (10−60 dilution), was chosen at random from twenty potential medicines.Results : Seven practising homeopaths were asked to make three guesses as to the identity of the remedy. Initially from the full list of possible remedies (N = 2372). Two of the seven homeopaths guessed the identity of the remedy correctly (p < 0.0001). Subsequently, when their choice of possible medicines was restricted to a list of 20, the same two homeopaths selected the correct medicine, however none of the other practising homeopaths did so (p = 0.2).Discussion : The selection of the correct homeopathic medicine from the unrestricted list (N = 2372 medicines) by two homeopaths is noteworthy given that the homeopathic medicine used during the HPT was diluted well beyond Avogadro's number and would not be expected to produce any detectable or recognisable symptomatology. Possible reasons why the remaining five homeopaths did not guess correctly are discussed.Conclusion : The results show that practising homeopaths may be able to correctly identify a homeopathic medicine from the set of symptoms generated during an HPT. This suggests that such symptom pictures generated by taking an ultramolecular homeopathic medicine are recognisable and specific to the substance taken. Since identification of the remedy was based on past HPT information held in the materia medica, this demonstrates that HPT-generated symptom pictures are reproducible, thus validating the HPT methodology. These promising preliminary findings warrant replication ; possible improvements to the trial design to be incorporated in future studies were identified.