The effects of the homeopathic preparation Vertigoheel on variables related to microcirculation were investigated using vital microscopy techniques in patients with vestibular vertigo. In a non-randomized, open study, 16 patients given Vertigoheel were compared with 16 untreated patients. Measurements were carried out in two areas (defined by selecting 60 blood-cell perfused nodal points of arterioles, venules, and capillaries with a mean diameter > or = 40 microm): the cuticulum/subcuticulum of the inside left lower arm and an area 5 mm behind the left earlobe. After 12 weeks of treatment, patients receiving the homeopathic preparation exhibited an increased number of nodal points, increased flow rates of erythrocytes in both arterioles and venules, increased vasomotion, and a slight reduction in hematocrit vs. baseline. None of these changes were observed in the control group and the differences between treatment groups were statistically significant. Partial oxygen pressure increased significantly in the Vertigoheel group compared with the control group. In addition, in Vertigoheel patients, significantly increased numbers of cell-wall adhering leucocytes were observed, accompanied by increased local concentrations of the adhesion molecules ICAM-1. The microcirculatory changes were associated with a reduction in the severity of vertigo in the actively treated patients, both as assessed by the treating physician and by the patients themselves. The data support a pharmacological effect on microcirculation from the treatment.