Oilseed flax and fibre flax both have the ability to produce stem fibre, though in different quantities. Oilseed flax varieties have not been consciously selected for fibre production. Fibre flax has been selected for high fibre content and quality instead of for seed yield or seed oil concentration, as is the case in oilseed flax. Previously there was no quick, easy method for determining straw fibre concentration inhibiting selection for stem fibre concentration in oilseed flax breeding programs. Near Infrared Spectroscopy (NIR) now provides a solution for this problem. Protocols for using the NIR on straw samples from beeding lines were developed from known high and low fibre flax lines. The results were correlated with actual fibre concentration obtained through retting thus providing a measure of the accuracy of the NIR for screening flax populations. Nine current oilseed flax varieties and one fibre flax variety were sown at three locations in Saskatchewan to determine what, if any, is the effect of the environment on fibre concentration. Another experiment was conducted to determine whether differences in fibre concentration can be detected in breeding lines from unreplicated single row plots. This would allow the screening for stem fibre concentration in early generation nurseries.