In this work we used x-ray structural analysis to investigate the martensitic transformations (MTs) B2⇌ R and R⇌ B19 in Ti(Ni, Fe) alloys containing 1, 2.5, 4, 5 at. % Fe, and the effect of heat treatment on the MT temperatures and sequence. In the majority of cases, it was found that the MT B2→ R proceeds through a two-phase region (β+ R). Heat treatment leads to a narrowing of the temperature interval of the existence of the two-phase region, weakly affects the onset temperatures of the MTs B2→ R TR and R→ B19 Ms, and sharply increases the temperature-of the end of the MT Me. The existence of the two-phase region is related to the two MT channels B2→ R and B2→ B19' initially intrinsic to the allovs of the given compositions.