I will present the review on results of studies of a new class of pulsating mass-accreting stars in the semi-detached Algol-type systems. I will discuss the advantages for studies of oEA stars for asteroseismology, the problem of non-radial mode identification and will show the typical peculiarities of this class of variables based on results of 14 years of photometric and spectroscopic monitoring of selected oEA systems.