Barley grains mutagenized with sodium azide were screened for high levels of free phosphate in order to identify low-phytate mutants. Approximately 2000 M2 half-grains were analyzed by molybdate staining and high free phosphate contents were scored positive for low phytate mutants. Plants were grown from embryo-containing halves of positive samples. Subsequent TLC analysis of positives was used to display free phosphate and phytate simultaneously, and two characteristic low-phytic acid phenotypes (A and B) could be distinguished. A-type grains, which were found for seven plants, contained very high levels of free phosphate, low levels of phytate and trace amounts of other phosphate-containing compounds not observed in wildtype samples. Migration of these novel P-compounds on TLC plates was similar to that of inositol phosphates other than phytate. In grains from the two B-type plants the increase in free phosphate and the decrease in phytate relative to wildtype levels were moderate and additional P-compounds were absent. Genetic tests showed that at least three recessive alleles caused low-phytic acid phenotype A, whereas a separate, recessive locus was responsible for phenotype B. The importance of these findings with respect to the development of new barley varieties with an improved nutritional and environmental value is discussed.