A sensitive and reliable voltammetric method for the determination of total alkannin using a glassy carbon electrode was developed. The method was applied to the determination of total alkannin in the roots of Alkanna tinctoria after hydrolysis of the isolated mixture of pigments consisting of alkannin esters. The detection limit was 0.55 mg l^–1 and the relative standard deviation 2.29%. For the accuracy of the method the hydrolysis step was crucial.