Vitamin B(12) contents of various Korean purple laver products were determined with the microbiological vitamin B(12) assay method. Although a substantial amount (133.8 microg/100 g) of vitamin B(12) was found in dried purple laver, seasoned and toasted laver products contained lesser vitamin B(12) contents (about 51.7 microg/100 g). The decreased vitamin B(12) contents in the seasoned and toasted laver products, however, were not due to loss or destruction of vitamin B(12) during the toasting process. Silica gel 60 thin layer chromatography-bioautogram analysis indicated that all Korean laver products tested contain true vitamin B(12), but not inactive corrinoid compounds. In vitro gastrointestinal digestion experiments indicated that digestion rate of vitamin B(12) from the dried Korean purple laver was estimated to be 50% under pH 2.0 conditions (as a model of normal gastric function). These results suggest that Korean purple laver products would be excellent vitamin B(12) sources for humans, especially vegetarians.