The objective of this study was to analyse milk traits (milk yield from morning milking, and fat, protein and lactose contents) and somatic cell count (SCC) in dairy sheep breeds in Slovakia: Tsigai (TS), Improved Valachian (IV) and Lacaune (LC), and their crosses (IV × LC and TS × LC). Milk performance testing was performed between 2010 and 2013. Mixed model for milk traits included fixed factors: SCC class (low, medium high), lactation number, month in milk, year-month of measurement, genotype, lactation number × month in milk interaction, lactation number × SCC class interaction, and random effects of ewe and residual error. Mixed model for log₁₀SCC (decadic logarithm of SCC) included the same factors except for SCC class and lactation number × SCC class interaction. Instead, covariates of milk yield and milk components were considered. Milk yield and lactose content decreased (P ≤ 0.05 and P ≤ 0.01, respectively), whereas fat and protein contents increased (P ≤ 0.05 and P ≤ 0.01, respectively) with increasing SCC. Similar trends were revealed when relationships between log₁₀SCC and milk yield and milk components were investigated through linear regressions and correlations (however, not all regressions were statistically significant, also correlations between log₁₀SCC and milk yield and between log₁₀SCC and fat content were very weak). To ensure the effectiveness of mastitis control programmes, further research is needed to understand an importance of somatic cells function as an indicator of health status which may affect ewe udder, milk yield and milk components.