Long non-coding RNA molecules (lncRNA) are defined as molecules over 200 nucleotides long that are localized in the nucleus and cytoplasm of cells. Although function of most lnRNA is not known, it is obvious that they are involved in various biological processes. LncRNA play a key role in transcriptional as well as posttranscriptional regulatory pathways and are involved in important cell processes, such as proliferation, differentiation, apoptosis but also pathogenesis of various diseases. Their dysregulation is important in steps of tumor transformation. In this review, we will describe the nature, function and molecular basis of these molecules as well as their diagnostic potential. The main focus of this review is the usage of these molecules in the most often diagnosed tumors in the Czech population--colorectal carcinoma, breast and prostate carcinomas.