The objective of this study is to describe patients who had treatment for hypersensitivity illnesses by general practitioners (GPs) or classical homeopaths (CHs) and the patients' self-reported effectiveness of the treatment received. The data stems from an exploratory retrospective study amongst 88 Danish patients (response rate 58%) suffering from hypersensitivity illnesses, who chose treatment from one of six GPs or one of 10 CHs who participated in the project. The patients themselves selected their treatment. The GPs or the CHs considered that the patient's treatment was complete or that the patient was in a situation of current 'maintenance treatment'. The patients' primary reason for consulting the GP or the CH was that they were suffering from hypersensitivity illnesses. No significant difference was found between the two groups of patients in relation to age, education and duration of hypersensitivity symptoms. The CH patients were more likely to be employed in teaching, research, health care or the social sector compared to GP patients. The two groups of patients were similar in respect of their health at the start of the treatment, 57% of the patients who consulted a CH experienced an improvement of their state of health compared to 24% of the GP patients. Both groups of patients experienced an improvement of their psychological health after treatment. Logistic regression analysis showed that the GP or CH was the only significant effect variable. The results are based on the patients' retrospective, self-reported effectiveness of the treatments.