Increasing emigration leads to the loss of investments in human capital as well as to the constraint of the knowledge economy via a huge leakage of demographical and intellectual capacity, hence threatening national security, social and economic stability. The target of the article is to examine the Lithuanian emigrants’ attitudes toward national security by analysing the relationship between emigration and national security, by disclosing the reasons for emigration, and by investigating the emigrants’ stance on national security. Long-term emigration lasting longer than a year has a greater impact on the country since most of long-term emigrants do not return. This is confirmed by the data revealing that most of emigrants live abroad for ten years or longer. Short-term (for less than a year) emigration can be qualified as a search for temporary financial improvement. It becomes evident amid financial crisis during which the loss of job opportunities and emigration leads to an increase in search for personal income and new experience abroad. Ninety four percent of participants of this research identify themselves as long-term emigrants, and 76% of them have a higher education. It points to the loss of educational investment and qualified labour force. The research reveals that most of survey respondents do not expect to return, for they do not trust the authorities. In addition, they deem that it is not reasonable to increase funding for the Lithuanian Armed Forces. The results of the study allow conclusions to be drawn that emigration is a real threat to Lithuania’s national security.