Length-weight relationships (LWRs) are investigated for three fish species which sampled with a beam trawl between September 2011-July 2014 in the Sea of Marmara, Turkey: Callionymus maculatus (Rafinesque, 1810), Gaidropsarus biscayensis (Collett, 1890) and Lepidorhombus boscii (Risso, 1810). The data of length-weight relationship were found with W=0.0042*L-3.13(n=20), TW=0.0090*TL2.74 (n=120) and TW=0.0108*TL2.92 (n=19), respectively. According to LWRs results C. maculatus showed positive allometry, G. biscayensis presented negative allometric growth and L. boscii isometric growth. The information about this issue are reported for the first time in the Sea of Marmara for such species. In this way this study is important with new results.