Chronic lymphocytic leukemia (CLL) is the most frequent leukemia in the Western adult population. The pathogenesis of CLL is largely driven by deregulation of non-coding RNAs, namely microRNAs and long non-coding RNAs (lncRNAs). LncRNAs are now gaining widespread attention for their role in the origin of various types of cancer as they represent a new crucial layer of biological regulation. However, there is only a small number of well-studied lncRNAs and mechanism by which they act is still rather unclear. This master thesis will focus on a thorough bioinformatic analysis of samples from CLL patients obtained by Next-generation sequencing (NGS). The student will i) identify potentially biologically significant lncRNAs in data from NGS ii) determine interactions and expression relationship between differentially expressed lncRNAs and other RNAs (including microRNA) iii) incline possible influence of uncovered RNA network on development and progression of CLL. Discovered RNA interactions could provide us with further insight into the biology of CLL.