Anamnestic and immunological data of workers of a platinum refinery (group A: workers with work-related symptoms, n= 8; group B: workers with symptoms not clearly work-related, n= 9; group C: asymptomatic workers, n= 13) and controls (group D: atopies, n= 10; group E: non-atopics, n= 16) were compared. Exposure to platinum salt was higher in group A than in groups B or C. In group A, symptoms developed 4 months (median) after the onset of exposure. All subjects of group A and three workers of group B, but none of the workers of the other groups, showed a positive cutaneous reaction to (PtCl6)2−. Total serum IgE was higher in groups A and D than in groups B, C or E.(PtCl6)2−-specific IgE was higher in group A, but there was non-specific binding of (PtCl6)2− to IgE. Histamine release with (PtCl6)2− was found in all groups and was highest in atopic controls. Histamine release with (PtCl6)2− and histamine release with anti-IgE showed an excellent correlation, suggesting a similar release mechanism of (PtCl6)2− and anti-IgE. In skin-test positive subjects, high cutaneous (PtCl6)2−-sensitivity is linked to high histamine release with (PtCl6)2− or anti-IgE, supporting the concept of a role of cell surface IgE or IgE-Fc-receptor in the release process with platinum salts. However, high specificity of cutaneous reactions contrasts with low specificity of in-vitro tests with (PtCl6)2−. A different reaction of basophils and mast cells, when challenged with free platinum salts, is hypothesized. We conclude that neither histamine release from basophils with (PtCl6)2− nor RAST for the detection of (PtCl6)2− specific IgE are helpful in the diagnosis of platinum salt allergy.