Dyeing with natural dyes from plant and other organic sources is known since the prehistoric times. In Latvia, natural dyes have been used for the colouring of natural fibres, such as flax, wool, cotton, silk and leather. Plants for the dyeing were collected in autumn in Latvia, used fresh or dried. Mordant ferrous sulphate, copper sulphate pentahydrate, potassium hydroxide, potassium dichromate and acetic acid were used before, during and after dyeing. The quality of dyeing was evaluated using the RGB system.