The objectives of this study were to determine the effects of genotype on chemical components of barley which influence nutritional value. Six barley (Hordeum vulgareL.) isotypes, expressed in Compana (CI 5438) and Betzes (CI 6398) cultivars with genetic combinations non-waxy (WXWX) and waxy (wxwx) starch in covered (NN) and hulless (nn) kernels and long-awn (LK 2 LK 2 ) and short-awn (lk 2 lk 2 ) traits, were grown in 1987, 1988 and 1989. Analyses were made for protein, fat, starch, free sugars, total dietary fibre (TDF ), TDF components and extract viscosity. The hulless gene reduced TDF by preventing the hulls from adhering to the kernel, thus concentrating the remaining components. Waxy barleys contained less (P<0·001) starch, but more (P<0·001) free sugars and ether extract (P<0·001). Increased (P<0·02) TDF in waxy barleys was due to an increase (P<0·001) in total and soluble β-glucans. The short-awn gene had no effect other than to increase (P<0·04) extract viscosity, and to reduce test weight (P<0·008) and % plump kernels (P<0·03). The expression of the hulless and waxy genes in barley is desirable for use in human food products due to increased levels of soluble dietary fibre, particularly β-glucans, but reduces malting potential and feed value for poultry.