Since the basic mechanisms that produce photometric variations, shell ejections, and eruptions of LBV’s are still unknown, it is worthwhile to investigate whether instabilities can occur when the improved self-consistent NLTE treatment of radiation-driven winds (see Pauldrach et al. 1986, Pauldrach 1987, Puis 1987, Pauldrach & Herrero 1988) is applied to objects lying in the LBV part of the H-R diagram. The motivation is obvious: LBV’s have lost considerable fractions of their initial masses and hence have L/M ratios close to the Eddington limit. For such objects, radiation-driven wind theory predicts not only a strong dependence of the mass-loss rate on the self-consistently calculated parameters k, α, and δ, which result from the NLTE occupation numbers of the 133 ions contributing to the line force, but also on Γ (= L/LEdd): Ṁ ~ k1/(α – δ) (1 – Γ)(α – 1)/(α – δ). Here we investigate the dependences of Ṁ on M (through Γ) and on the physical environment of the atmosphere (through k, α, δ) separately. The calculations are performed over a large model grid of stellar parameters for P Cyg, a typical LBV (see Fig. 1).