Lymphocytes are the carriers of acquired immunity. They originate from primary lymphoid organs. In secondary lymphoid organs they are activated by antigen and become mature effector cells. In secondary lymphoid tissues there are germinal centers, sites where B-lymphocytes undergo maturation process. The germinal centers are characterized by very high cell proliferation rate and frequent and rapid cell divisions preceded by DNA replication. Replication is under strict control of the complex system of enzymes and proteins. If changes in their expression occur, result could be dysregulation of cell cycle control and replication. Such abberations are particularly common in tumors originating in secondary lymphoid tissues. Aim of this study was to analyze the expression of proteins involved in cell cycle regulation and replication: MCM2, PCNA, GMNN, DNMT1, p300, CDT1 and EZH2 in lymphoma development. 35 samples of non-cancerous tonsils and lymph nodes of patients with follicular lymphoma as well as diffuse large B-cell lymphoma were used. By using immunohistochemical staining, the amount of cells expressing proteins of interest was determined. Statistically significant difference in the amount of cells expressing MCM2, PCNA and EZH2 was found when non-cancerous tonsil cells were compared with lymphoma cells. Comparison of the amount of tumor cells of follicular lymphoma and diffuse large B-cell lymphoma showed statistically significant differences in the expression of MCM2, DNMT1, CDT1 and GMNN. The results indicate that these proteins are included in cell proliferation, but also show their potential role in lymphoma formation.