A dissertation submitted in partial fulfillment for the requirements of the master of science degree in agricultural and applied economics of Sokoine university of agriculture. Morogoro, Tanzania.This study was done to assess the East Africa Community (EAC) Non-Tariff Barriers (NTBs) and their effects on Tanzanian small and medium agro enterprises (SMAEs) engaged in EAC cross border trade. Specific objectives were; to describe the structure and characteristics of Tanzanian SMAEs; to examine determinants of Tanzanian SMAEs engagement in EAC cross border trade, to identify NTBs that affect Tanzanian SMAE’s engaged in the EAC cross Border trade; and, to analyze the effect of identified NTBs on Tanzanian SMAEs trading in the EAC cross border trade. Both secondary and primary data were collected from Arusha, Mwanza, and Kagera. The number of respondents who comprised owners of SMAEs was 105 for those who were trading locally within the country, and 105 for those who were engaged in the EAC cross border trade. Agricultural goods selected were maize, beans and rice as major crops traded within the EAC region. Descriptive Statistics and Binary Logistic linear regression model were used to examine determinants and characteristics of Tanzania SMAEs engaged in EAC cross border trade. Costs and Benefit Analysis method was used to ascertain the projected Net Present Value between exporting agricultural products to EAC countries and trading similar products within the country , and to analyze the effect of NTBs. The results indicate that SMAEs engaged in EAC cross border trade are affected by 26 % of additional transport costs resulting from NTBs. However, there are potential benefits to be earned by SMAEs engaged in cross border trade if NTBs are reduced. Major recommendations are as follows; i) Government and private institutions should decentralize to help in registering and monitoring Agribusiness sector at regional and district level and help to abolish NTBs ii) Increase the pace of harmonizing the trading procedures and policies in the EAC region to assist in smoothing trade activities