It is well established that sulfate fertilisation significantly enhances the content of mustard oil glucosides in glucosinolate containing plants. However, with respect to tissue cultures and in vitro-plants, corresponding data are missing. In this study the influence of sulfur on the accumulation of glucosinolates was analyzed in nasturtium in vitro-plants (Tropaeolum majus). The glucotropaeolin content in plants grown on standard media (MS) varied between 10 and 50 μmol/g DW, corresponding to only about 20 % to 70 % of the glucotropaeolin content in earth grown plants. A fivefold enhancement of the sulfate concentration resulted in a massive increase in the glucotropaeolin content of the in vitro-plants. A decline of sulfate in the medium leads to corresponding diminutions of the glucosinolates accumulated. These data clearly demonstrate the high impact of sulfur availability on glucosinolate biosynthesis and accumulation