UDP-glucose pyrophosphorylase is a common plant enzyme and plays a key role in many processes connected with carbohydrates metabolism in plant tissues. This enzyme catalyse the reversible reaction of synthesis/degradation of UDP-glucose and inorganic pyrophosphate from glucose-1-phosphate and UTP. UDP-glucose is the precursor of many carbohydrates like sucrose, starch, pectin, cellulose. The second product of UGPase activity is PPi, the alternative to ATP energy donor which supply Pi. The highest activity of UGPase was observed in cytosol. In mature leaves UGPase takes part in synthesis of sucrose and other carbohydrates (in cooperation with sucrose phosphate synthase). In sink tissues UGPase cooperates with sucrose hydrolytic enzyme sucrose synthase in sucrose degradation. It seems that it also plays an important role in endosperm development and sulfolipids biosynthesis in chloroplasts. UGPase plays role in cold sweetening of potato tubers, which were stored in cold temperature, and that process is unfavourable in food industry. There are many external and internal factors, which have an influence on UGPase genes expression and activity. Oligomerization is an internal factor. UGPase could occur in few forms but only monomer is an active form in plant tissues. External factors include environmental condition such as light, temperature, nutrient (phosphorus, iron) and other factors like availability of sucrose, mannose or okadaic acid. Stress conditions significantly change expression of UGPase genes, enzyme activity and regulate sucrose and the other carbohydrates synthesis/degradation. It was observed that reduction of UGPase activity had an visibly influence on sugars content. Such modification in carbohydrates metabolism are essential to plant acclimatisation in changing environmental conditions. That is the reason, why UGPase which was not perceived as an important enzyme in carbohydrates metabolism, takes the value. In last few years the knowledge about UGPase has increased especially about control of genes expression, protein structure and enzyme activity regulation. This review presents short description of role of UDP-glucose pyrophosphorylase in metabolic processes in plant tissues.