Small and medium enterprises (SMEs) in Thailand are fundamental business units spread all over the country. Since the severe economic crisis (i.e., Tom Yum Kung disease) in 1997, thousands of SMEs have gone bankrupt and so dropped out of the Thai economy each year. One key means of enhancing the viability of SMEs and assisting in economic recovery of the country that has been suggested is to transform them from a traditional to digital business using the Internet and e-commerce.. The expected advantages of e-commerce strategy include decreasing costs, expanding marketplaces, enhancing competitiveness, improving business image, and increasing revenues. However, there are snares and hidden pitfalls in the backend of this business. This chapter presents an overview of e-commerce of SMEs in Thailand. The first part introduces fundamental background of SMEs in Thailand including types and characteristics. The second part investigates advantages and disadvantages of e-commerce implementation. Finally, the third part discusses SMEs and e-commerce in Thailand in the case of e-tourism.