A literature review of biogenic sources of NOx was conducted to determine their emission rates into the atmosphere. NOx are some of the products of microbial denitrification, chemical decomposition of nitrites and the oxidation of organic nitrogen compounds. There appears to be no significant emission of NOx from either oceans or freshwaters. Biogenic emission rates for NO and NO2 from soil range from 0.015 to 0.02 kg NO sq km/hr and 0.01 to 0.2 kg NO2 sq km/hr. Submerged soils, sediments, marshes and swamps could be sources of NOx but emission data are not available. There is no significant evidence of NOx emission from living vegetation. During decay, decomposition and ensiling of vegetation, NOx can be formed. The estimates of NOx emission rates from the above biogenic (soil) sources were computed for a global basis and then compared closely to previously estimated natural global emissions.