This thesis is about properties and applications of flax fibre reinforced biocomposites. Today, when ecological consciousness grows, the use of natural materials that do not have a negative impact on the environment and have the ability to recycle and reduce energy consumption during production, is an environmentally acceptable alternative. Theoretical part of the thesis gives an insight into the advantages and disadvantages of composite materials, advantages and disadvantages of natural fibres and the production methods of natural fibres. Special emphasis is put on the flax fibres, structure of the fibres, their mechanical properties, advantages and disadvantages. Experimental part describes the making and mechanical testing of the composite material which consists of polyester resin based matrix and flax fibres as reinforcement. Also, a flammability test was carried out. The results of mechanical testing are low tensile modulus and low tensile strength, high flexural strength and flexural modulus, good toughness and high hardness. The studied flax composite material was not self-extinguishing. Potential applications of this composite material would be in the automobile industry for interior of automobile or for the modern manufacture of furniture and interior wall linings that can be used in construction industry. Considering the not self-extinguishing properties of the studied composite material, other resins with added fire retardants should be tested.