Thiamin is an essential vitamin that a lot of species are currently suffering a deficiency in. One being Atlantic cod in the Baltic Sea, especially in the Baltic Proper. A deficiency in thiamin has a variety of negative health aspects, mainly neurological damages and in fish such as cod increased offspring mortality. This study investigated if there was a difference in thiamin concentrations of female cod gonads at different maturity stages of cod between cod stocks in the Baltic proper (eastern) and cod stocks in Kattegat, Skagerrak as well as the North Sea (western). Three different vitamers of thiamin in the gonads were measured and then calculated to a total amount of thiamin and compered between the eastern and western stocks. The thiamin concentrations were significantly lower in the western stock. However, when accounting for the total amount of thiamin in the whole gonad and not only the concentration there is no longer any difference present. Thiamin concentration also seems to increase with gonad maturity, at least until the beginning of the spawning stage. More research is needed to further explore the thiamin status in the Baltic Sea, especially for western cod stocks.