Natural fibres well protected against biodeterioration and with barrier properties can be used in many new applications. The study aims at using eco-friendly biocides, not used in textile industry so far, for antimicrobial finishing of natural fibres. The research was carried out on flax fibre and linen fabric protected with biocides based on amono-boron-copper compounds, natural biocides and ionic liquids as new QACs. The flax fibre was subjected to action of mixture of fungi most often causing decomposition of cellulose in high humidity conditions. Evaluation of antibacterial properties of treated fabrics was done using qualitative method in presence of synthetic sweat against groups of bacteria present on human skin.