Vitamins are of crucial importance for human health because insufficient intake can cause different diseases. When it's impossible to ensure a sufficient intake of vitamins through the diet, people use dietary supplements. Usage of dietary supplements must be strictly controlled because the excessive intake of vitamins can also be harmful. For that reason, it's important that the amount of vitamins stated on the label of dietary supplement matches the actual amount. To control whether that's true, we need accurate, reliable and fast analytical methods. Some of the most used ones are liquid chromatography, capillary electrophoresis, voltammetry, spectrofluorimetry and supercritical fluid chromatography. This thesis contains short theoretical background for each of these methods, optimal conditions when using them for determination of vitamins in different types of dietary supplements and the most common ways of preparing such samples for the analysis.