The biogeochemical cycle of silicon was studied at the Kerguelen Fixed Station (KERFIX) between 1992 and 1994. The timeseries shows a seasonal use of the stock of silicic acid decoupled from that of nitrate. Thus, silicon probably plays an important role in limiting the primary production of diatoms in that area, characteristic of the permanently open ocean zone. Despite this, given their very low growth rates, the dominant diatoms are strongly silicified. The results of KERFIX are compared with more recent KEOPS (Kerguelen Ocean and Plateau compared Study) results and provide a complement to KEOPS in terms of understanding interannual and seasonal variability.