In this paper we analyze the exact boundary behavior of solutions to singular nonlinear Dirichlet problems −△u=b(x)g(u)+λa(x)f(u),u>0,x∈Ω,u|∂Ω=0, where Ω is a bounded domain with smooth boundary in RN, λ≥0, g∈C1((0,∞),(0,∞)), lims→0+g(s)=∞, b,a∈Clocα(Ω), are positive in Ω, may be vanishing or singular on the boundary, and f∈C([0,∞),[0,∞)). We reveal that the nonlinear term λa(x)f(u) does not affect the first expansion of the classical solutions near the boundary to the problem for several kinds of functions a and b.