Emergent fluxes from a non-LTE model atmosphere code designed to calculate realistic O star atmospheres are applied to nebular calculations. The stellar models include wind and blocking effects due to several million doppler-shifted lines in the radiation driven atmosphere in a full NLTE treatment. These lines, which arise from heavy elements, reduce the stellar flux drastically between 228 and 912 å (Pauldrach et al. 1994) — the most important frequency regime for ionization in gaseous nebulae. We have three models with effective temperatures of 50000, 40000 and 35 000 K and log g values of 3.9, 3.8 and 3.5 respectively. They have been used to model Hii regions and their use has led to significant differences in the ionization structure of the nebular models.