When making any financial decisions, it is very important that we are aware of all options offered to us on the market. Cryptos are still relatively new financial instruments that we meet on the market, and their development is related to the development of new information technologies. The specificity of the cryptocurrency is that they have greater resistance to economic shocks, which is in fact one of the main reasons why investors want to include them in their portfolio. The main objective of this paper was to investigate whether the inclusion of cryptocurrency will increase the yield of portfolios, we will check whether cryptocurrencies are really low correlatedand, how the inclusion of cryptocurrencies will affect the efficient frontier or whether the efficient frontier of cryptocurrencies will be above or below the efficient frontier composed of a portfolio of stocks from individual markets. Based on the calculation of weekly expected yields, efficient stock portfolios and efficient cyrptocurrency portfolio, correlation matrix and established efficient frontier, we have determined that cryptocurrencies are low-collated in relation to each other's shares, the inclusion of cryptocurrency in the portfolio has improved its performance, and that the efficient frontier is partly above the efficient frontier composed of stock portfolios from individual stock markets.