This paper focuses on a set of factors related to the opportunity motivations of early-stage entrepreneurs, such as entrepreneur's perceptions and socio-demographic factors. The research area of this paper includes: fear of failure, social networking, entrepreneur's knowledge, skills and experience, and perception of business opportunity; and socio-demographic characteristics of entrepreneurs, such as the age, gender, level of education and household income. The data has been provided by Adult Population Survey, as part of the Global Entrepreneurship Monitor. The sample includes data collected in 2014, from 12,023 adults by interview methods, which implies valid answers of 692 early-stage entrepreneurs, i. e. a total of 415 early-stage entrepreneurs driven by opportunity motivation. The respondents are located in the Southeast Europe (SEE); and settled in six countries: Greece,

Research area of this study includes determinants that have an influence on international ventures of early-stage entrepreneurs, nascent and new business owners. The research implies determinants such as: entrepreneurial motivation, innovation activity, use of new technology and demographic factors-gender and age. Data for the research was provided by the Global Entrepreneurship Monitor database; the sample covers data of early-stage entrepreneurs who settled their business in Southeast Europe. The methodology of empirical research provides a presentation of statistical research by using Probit regression and concept of marginal effects. According to the aim of this paper, the model was created by setting the determinants that influenced the internationalization activity. The research results show that increase-wealth opportunity motivated early-stage entrepreneurs, internationalize more than the necessity entrepreneurs or early-stage entrepreneurs driven by the motive of independence. Early-stage entrepreneurs, who use new technology and prefer radical innovations, are more oriented on foreign markets and customers. Also, there is a significant influence of demographic factors such as entrepreneurial gender and age on internationalization activity. Analysis of entrepreneur's internationalization at the country level shows the differences between the countries of Southeast Europe.