A hundred samples of total diets, 19 samples of cheese (mainly Dutch), a total of 30 samples of muscle, fat liver, kidney, blood and fried meat from experimental veal calves (fed daily with 0.6 or 300 mg of potassium nitrate per kg b.w.) and 14 samples of urine of patients medicated with massive amounts of ammonium nitrate (up to an equivalent of 180 mg potassium nitrate per kg b.w.) have been analysed with GC-TEA for their content of the following N-nitrosamines: NDMA, NDEA, NDPA, NDBA, NPIP, NPYR and NMOR. NDMA was frequently found, but always in the sub micrograms per kg range, except for two diets (1.2 and 1.7 microgram/kg). Other N-nitrosamines were sporadically found in the same concentration range, except for one diet (NPYR, 1.9 microgram/kg). No correlation was found between NDMA content and the composition of diets or the nitrate load of patients or veal calves. Mean daily intake of NDMA, potassium nitrate and sodium nitrite from total diets was calculated to be 0.5 microgram, 215 mg and 7.7 mg respectively. N-nitrosamine recoveries from the various samples were determined mostly at the 1 microgram/kg level. Contents of potassium nitrate and sodium nitrite are reported for 124 samples of various vegetables, 94 samples of canned baby food and 48 samples of human saliva, collected at various times after the intake of meals. Some kinds of vegetables showed high to very high nitrate contents, for example, purslane, red beets, spinach and lettuce. Only traces of nitrite were found in the vegetables. Salivary nitrite content was shown to be highly dependent on the dietary intake of nitrate and increased up to 60 times its initial value after the consumption of vegetable-rich meals.