Abstract
This paper presents α (16), α (35), Γ (9) and Γ (16) indices for twenty O-type stars and three T Tauri-like objects. It is confirmed that Hα is an excellent luminosity indicator of the O star's luminosity. The multiplet neutral oxygen lines at λ7774Å for O-type stars, on the average, have the same strength as in the Sun. Hα and OI for T Tauri-like objects may be contaminated by emission, and probably they also vary with time. Hence, their use as luminosity criteria may not be adequate in many cases.
