We consider the problem of determining indices for periods with non-constant prices. The structurally-dynamic quantity indices and price indices-deflators of value flows are induced for aggregated periods consisting of the sequences elementary and homogeneous ones (which can not be represented as a series of others with less duration). These indices depend on changes in the quantities and average prices of products in these sequences. So they are distinguished from the traditional static in­dices, defined only by amounts of values and quantities of products in the aggregate periods. The definition of indices, consistent in reference to aggregation of products, which is natural for practical uses, is suggested. Recommended chained Divisia – Montgomery price indices possess such a property. We also consider an alternative definitions of homogeneity of period with non-constant prices and the corresponding methods of calculating average product prices on the base of available statistical data. The definition based on the properties of Divisia – Montgomery indices is preferred.