This bachelor thesis is focused on illegal labour market in the Czech Republic. The first part includes definitions regarding labour market and illicit work. There is specified the difference between shadow economy and illicit work and there are indicated measuring methods in this part of economy. It includes the percentage part of shadow economy within GDP in all European countries, which are compared with the Czech Republic too. In the second part an analysis of many misting methods of execution of hidden work was made to define economic impacts. Moonlighting was indicated, part-time illicit work, complete illicit work, work of migrants, hidden incomes and increased expenses of entrepreneurs and dodges which are called as "švarcsystém" in...