Nitrosamines are an extremely carcinogenic class of compounds. The hasard, bound with the occurrence of this compounds in the food and the possibility to be formed in vivo, during the digestion, justifies the current works. The authors quoting numerous works on different laboratory's animals, remind the toxicity. and carcinogenicity of this compounds. The metabolism is also discussed. The N-nitroso, compounds may be formed in food from the presence of the precursors (nitrite or nitrate, amines and amino-acides). The synthesis takes place during the technological processes, the storage and the house cooking. Today, the marginal effect dose is estimated as 10 mug/kg of daily food. The carcinogenicity has not been demonstrated in human, but is strongly suspected. The amount of N-nitroso compounds in human food is generally low. Many factors can influence the reaction; it is inversely related to the basicity of secondary amine and optimum pH is around pH 4. A lot of compounds such as sodium ascorbate inhibit the synthesis in food. A number of recent reports using reliable methodology have identified nitrosamines at the lower part per billion level. Dimethyl-nitrosamines occurs, very sporadically in a number of cooked meat samples. The nitrosopyrrolidine appears frequently in fried but not in uncooked products. The nitrosopiperidine seems to be bind with the presence of pepper in food. Finally the presence of nitrosamides (nitrososarcosine) and nitrosoaminoacides (nitrosoproline, nitrosohydroxy-proline) is being quested. The N-nitroso compounds may be synthetized in vivo during the digestion at the acide medium of the stomach or by bacterial action during the transit in the gut...