Abstract Vegetables contain higher concentrations of nitrate than other foods and make the major contribution to dietary intake. This is present naturally, or may be present as a result of the use of fertilizers on crops, or from its use as a preservative. There have been health concerns about the presence of nitrate in food as it can be metabolized to potentially carcinogenic N-nitroso compounds. The main sources of NO3°¥ and NO2°¥ in diet are vegetables and meats. According to the U.S. Department of Agriculture the average adult ingests about 25 mg of N-NO3 per day in foods. Varamin is the most important county for agriculture in Tehran Province. During the last set of researches, many scientists made studies about the effective factor of Nitrate in plants. But none of the local studies calculated Nitrate in harvest of local plants. (For example Varamin) In this study, at first, the fields were chosen at random, from fields that use the same type of Nitrate fertilization. This study was almost all about the Varamin area. Content NO3°¥ in lettuce was determined with sampling in different seasons and different hours of the day (3 replications in any field). The nitrate (NO3°¥) contaminant levels of lettuce compared with general standard (FAO, EC, WHO standard) with T.TEST. During this study, in two seasons seed plant, (spring and fall) near the harvest, content Nitrate in plant measure at 4-8 am and 14-16 pm at the same day. The standards (EC & WHO) permitted nitrate maximum concentration is 3000 ¨C 3500 ppm. We found that the NO3°¥ content in the morning was much lower than in the afternoon. With EC standard we observe that all sample had NO3°¥ pollution. In the lowest form the nitrate content was in lettuce leaf 4287 ppm and in the highest form 13304.2 ppm. We have significant difference (%1) between our measurements and all of our samples had NO3°¥ pollution. Key Words: nitrate (NO3°¥) contaminant levels, soil pollution, NO3°¥ pollution, lettuce, Varamin County.