High performance liquid chromatography, using either reverse phase, anion exchange or chromatofocus mg columns was used for the resolution of hordems extracted from Irish barley varieties. The possibility of using the hordein elution profiles for the routine identification of Irish barley varieties was investigated. Extracted hordems were well resolved with the two reverse phase columns used in the present work and the difference between the elution profiles of the thirteen varieties examined were very obvious. It was possible to reduce hordein elution times for the reported 110 minutes to about 50 minutes without loss in resolution by using a C4 rather than C18 column. As the hordein profiles were repeatable even after extended column use, they can be used for the positive identification of Irish barley varieties. Hordein elution profiles characteristics of a particular variety were also obtained with anion exchange column and chromatofocusing, but the resolution with both was much poorer than with reverse phase columns. The repeatability of hordein profiles with anion exchange columns was poor, resolution deteriorated rapidly after five injections and elaborate column cleaning was required to restore it Repeatability was somewhat better with chromatofocusing but also a lengthy column cleaning was required after every ten injections. For both columns hordein profiles obtained before and after column cleaning were different, hence the techniques in their present form cannot be used for varietal identification. The two most commonly used methods for the determination of 6-glucan levels namely the cellulase and the lichenase assay were evaluated. Considerably higher total 13-glucan levels were obtained with the cellulase than with the lichenase assay but it was not possible to establish from the available data which was the more accurate method However, as the lichenase assay is the preferred method of the brewing industry it was used for estimating the effect of variety, agronomy and environmental factors on 6-glucan levels in barely Varietal effect on 8-glucan levels was evident, intervarietal differences were statistically significant and even if 8-glucan levels for all varieties changed with season, the order of values remained constant. Autumn sowing dates had no effect on B-glucan levels at two locations and the effect of applied nitrogen at three locations was inconclusive. A strong environmental effect on 8-glucan levels was also noted, in that levels seem to be effected by soil moisture during gram filling and decline with decreasing soil moisture. Barley samples used for the determination of external effects on B-glucan levels were micromalted to evaluate external effects on B-glucanase levels in malt. The "dye- labelled B-glucan assay" was used for the determination of B-glucanase levels in these samples, because it was found to be the most precise of the three reported methods evaluated by an independent study. The other two methods were viscometry and radial diffusion assay. There was a definite varietal effect on B-glucanase as the differences between levels corresponding to the six varieties were statistically significant and the order of values remained constant for two seasons. The environmental effect was also shown by the fact that three varieties had consistently lower B-glucanase levels in one of three locations, at different rates of applied nitrogen. No explanation could be advanced for the observed effect Different autumn sowing dates had no obvious effect on B-glucanase levels in malt.