Allergenic potency assessed by the 50% RAST-inhibition endpoint titration was compared with enzyme titration for the analysis of commercial pollen extracts. Six different extracts of short ragweed, orchard grass and perennial rye grass were examined. A good correlation (p < 0.01) was found between the acid phosphatase titers and allergenic potency of short ragweed and perennial rye grass extracts. A similar correlation (p < 0.01) was observed between leucin amino peptidase titers and allergenic potency of short ragweed extracts. No correlation could be found with orchard grass extracts. These findings suggest that enzymatic activity may provide a method for the control of certain commercial pollen extracts.