The quality of most garlic (Allium sativum L., Alliaceae) preparations made from garlic powder or garlic dry extract is determined by their content of alliin. Therefore, a comprehensive documentation of alliin concentration beginning with the crude material up to the final remedy is required. The newly developed analytical method described in this paper was designed in order to fulfill these demands. In contrast to conventional HPLC methods, neither a pre-column derivatization nor a chromatographic separation are involved in this analytical procedure allowing a high throughput of samples. The currently investigated technique is based on immobilized alliinase (EC 4.4.1.4) which was combined with a two-channel flow injection analyser (FIA) coupled to an ammonia detecting device. A high specificity for alliin could be demonstrated and a variety of garlic samples including garlic powders, dry extracts, and garlic preparations was analysed. The results were in good correlation with those obtained by conventional HPLC methods.