Résumé
Line-blanketing effects in atmospheres of O-type stars are studied based on models computed with the non-LTE spherically expanding code cmfgen (Hillier & Miller 1998). We show that the inclusion of metals leads to a reduction of the effective temperature scale by ~ 1500 K at spectral type O9.5, up to ~ 4000 K at spectral type O3. This change of the T eff scale implies a reduction of the luminosity by ~0.1 dex and a decrease of the ionising flux by ~ 50% for a given spectral type.