Linseed (Linum usitatissimum L.) var 'Janaki', 'Surbhi' and 'Nagarkot' were analyzed for starch, total sugars, reducing sugars, non-reducing sugars, unavailable carbohydrates, calcium, phosphorous, iron, zinc, antinutritional factor, phytic acid and phytate phosphorous. In vivo protein quality was estimated by feeding to rats and estimating feed efficiency ratio (FER), protein efficiency ratio (PER), nitrogen balance, apparent protein digestibility, biological value, net protein utilization (NPU), net protein ratio (NPR), protein retention efficiency (PRE) and the weight of liver, kidney and spleen. Varietal differences were observed for all the parameters. 'Surbhi' contained higher amounts of carbohydrates and dietary fiber whereas 'Nagarkot' was rich in minerals and had better in vivo protein quality. Incorporation of linseed in the diets of rats at 25% level showed higher biological value, NPU and PER.