The Covid-19 pandemic brought changes to every country’s economy. The increasing number of cases, the lack of equipment and supplies, and the disruption of production and services, led to strong measures to stop the spread of the virus. The pandemic also had a significant impact on the stability of existing businesses. The announcement of lockdown and the resulting restrictions influenced consumer behaviour, and companies have had to adapt quickly to current changes in order to maintain economic security. The suspension or restriction of activities affected the income, profits and business continuity of companies. The main purpose of this article is to analyse how the Covid-19 pandemic affected the economic security of small and medium-size Lithuanian companies. What impact did the pandemic have on the Lithuanian economy and the business dynamics of organisations? Using research methods, scientific literature and statistical data, a comparative analysis was performed to assess the impact of the Covid-19 pandemic on Lithuanian organisations. Based on the results, Lithuania was the least affected by the pandemic in the context of the European Union. However, there was a lot of uncertainty at the beginning of 2021; but the economy grew faster than expected. The volume of industrial production increased, retail and international trade grew. Despite the pandemic, growth was maintained in the manufacturing, wholesale and retail sectors. The impact of the pandemic was felt most in the services sector: accommodation and food service activities, the arts, entertainment and recreation, service and administrative activities.