The diploma thesis covers the concept of International sales and management of key customers. In order for companies to have successful sales, a lot of knowledge and skills are needed. They need to constantly learn new trends and keep up with modern sales, if they want to succeed and sell well. Sales managers have a key role and responsibility in sales planning and sales evaluation. They also pay attention to the size of the sales force, which is obtained by dividing the total number of sales visits that need to be made during one year by the average number of visits that can be made by one salesperson during the year, so that everyone has approximately the same conditions. The role of international trade in the economic development of the world is great because international trade contributes to the development of the economy itself, as well as the economy of countries. Key Account Managers are of special importance and value for the company. For this reason, they should be approached in a special way so that the elementary aspects are not neglected and in order to achieve permanent maintenance and improvement of the relationship between the seller and the buyer. This is why Key Account Management has grown in importance in the last 20-30 years. This importance of key customers for the company results in the concentration of forces directed towards the key customer and the creation of activities oriented and adapted to the key customer. The marketing concept itself, including its Key Account Management, and their implementation, represent a challenge for the company. Understanding the need and importance of the existence of Key Account Management in the company is no longer questionable. This concept has been accepted by successful companies for a long time, and those that haven't are losing the market competition and will have to quickly implement it in their business plan. The joint opportunities for growth and development of the bidder and the key customer are recognized and they strive to make positive use of them. The goal, between these two interested parties, is to create such a situation in which both parties will profit.