Due to solid economic growth, the Czech economy faces increasing labour shortages. The gap between labour supply and demand is partly filled with migrant workers from Ukraine and other former Soviet Republics. Usually paid much less than Czech workers, Ukrainians and Moldovans help to maintain the Czech economy's growth. Despite this economic benefit, citizens of countries of the Commonwealth of Independent States (CIS) have only limited opportunities to work legally in the Czech Republic. In most cases, would-be migrants depend on the services of intermediaries, or so-called clients, to organise their stay. The client services are not provided free of charge; the common exploitation of migrant workers and the connections between clients and organised crime have recently become the topic of several studies (Cerník, 2005a, 2005b; Cervinka, 2004; INTERMUNDIA, 2005) which indicates the growing political concern. How can the rise of the “client system” be explained? In this paper, I will, after a brief outline of methodology and terminology, present and discuss three mutually complementing approaches to examine the phenomenon: historical, functionalist and post-structural. The first two approaches summarise the research discourse in the Czech Republic whilst the last point of view goes beyond these “traditional” perspectives on the client system. Using studies by leading experts on social organisation in the post-Soviet hemisphere and deploying some of the models developed by these authors, I will attempt to “decompose” the client system into some of its constituent elements such as the principle of mastership, reket technique and krysha concept. My contribution is based on preliminary research (non-standardised interviews) with respondents who have experienced the so called client system. Additional information was taken from the mentioned ethnographic studies dealing with the informal economy in post-socialist countries.