Physiological investigations were made on 25 barley (Hordelllll vulgare L.) landraces andrnacceSSIOns to screen for fi'ost resistance. Samples were collected fi'om three sites, in Amhararnadministrative rcgion, north Wolo and Tigrai administrative region, south and east Tigrai (northrnEthiopia) in November 1999. Experimental work was conducted fi'om January to March after thernseedlings have been grown for about a month in an open field at the Science Campus, AddisrnAbaba University. Accessions fi'om mCR were included for altitude ranges from which fieldrncollections were not made. Etlmobotanical study was also conducted in order to get infOimationrnon the indigenous practices that may be enabling fanners to continue barley cultivation in fi'ostrnprevailing areas.rnIn the surveyed areas, at least half of the fatmlands of the peasant fanners were prepared forrnbarley cultivation during the main rainy season, the rest being for legumes as well as wheat. Therninterviewees indicated enviroillnental stresses such as insufficient rainfall, low soil fertility andrnfi'ost effect as main limiting factors of barley production. They also responded that none of themrnhad ever practiced selection of barley for resistance to fiÂ·ost. However, early maturing barleyrntypes are cultivated in higher altitudes when there is scarcity ofrainfall, which also escape severernfiÂ·ost. The late bariey landraces were neglected by the fatmers due to the unreliable rainfall. Thernethnobotanical investigation indicated that barley is used as a major food grain alone or inrncombination with other cereals utilized in different forms of foodstuffs. Moreover, it has bothrnreligious and cultural values.rnA total of 25 samples were evaluated using conductivity and chlorophyll a fluorescence methods.rnBased on membrane stability and fluorescence studies, the potential survival temperature of the samples rangcd from -6.48 Â°C to -8.64 Â°C. Barley landraces from Abune-Yosef, Smp3rn(Tedowasha) and Smp13 (Awarye), which were collected from altitudes of 3270 and 3300m as.rnas well as accessions AccS (Kokufa) and Acc2 (Chellka) from Bale altitude of2430m and l6S0mrnas., respectivel y were found to be relatively the most frost resistant in both methods. SamplesrnSmp21 (Saeda-Shewa) from Tsibet-Embahasti altitude of3100m as. as well as Acc3 from Arsirnaltitude of 2800m as. were found to be relatively the most susceptible in conductivity andrnfluorescence analysis methods, respectively. The study showed that -5Â°C (using conductivityrnmethod) and -4 Â°C (using fluorescence analysis) were the highest sub-zero temperatures at whichrnthe samples could be differentiated easily. Altitude of site of sample collection had a slightrnpositive correlation with fi'ost resistance. The two methods had consistency and showedrnvariations among the samples and are thus recommended for screening barley landraces andrnaccessions. Fluorescence analysis was found to be a more sensitive method.