In this paper we present a combined photometric, spectroscopic and orbital period study of three early-type eclipsing binary systems: XZ Aql, UX Her, and AT Peg. As a result, we have derived the absolute parameters of their components and, on that basis, we discuss their evolutionary states. Furthermore, we compare their parameters with those of other binary systems and with the theoretical models. An analysis of all available up-to-date times of minima indicated that all three systems studied

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... ere show cyclic orbital changes, their origin is discussed in detail. Finally, we performed a frequency analysis for possible pulsational behavior and as a result we suggest that XZ Aql hosts a δ Scuti component.