Based on various statistic and documentary sources, the present paper follows the evolution of the United Romaniaǯs population in the interwar period in a general European context, identifying both general and specific features. Although it had an oscillating evolution, Romaniaǯs population was, in the interwar period, one of the most dynamic in Europe, one of the essential features of its demographical evolution being the vital capacity, its birth rates surpassing other countries. This fact enabled Romaniaǯs natural population increase to remain significant, although in the interwar period infant and general mortality had high rates.