Abstract. Studies concerning associations between candidate gene polymorphisms and milk production traits in cattle are carried out on a large scale (CITEK et al. 2007, KULIG 2005). Stearoyl-CoA desaturase (SCD) is the enzyme involved in conversion of saturated fatty acids into monounsaturated fatty acids. The gene encoding SCD was mapped to bovine chromosome 26 (CAMPBELL et al. 2001), where some QTLs for fat yield and other milk production traits as well as for somatic cells count (SCC) were also identified. Some of the SNPs identified within the SCD were significantly associated with fatty acid composition in milk and in carcass fat tissue (MOIOLI et al. 2007, TANIGUCHI et al. 2004). The effect of genotypes on milk production traits and SCC in cattle has not been reported so far. The aim of this study was therefore to establish possible associations between two SNPs in the SCD and milk production traits and SCC in Jersey cows.