We consider the general nonlinear heat equation ∂ t u = ∆u+a|u| p 1 −1 u+g(u), u(0) = ϕ, on (0, ∞) × IR n , where a ∈ IR, p 1 > 1 + (2/n) and g satisfies certain growth conditions. We prove the existence of global solutions for small initial data with respect to a norm which is related to the structure of the equation. We also prove that some of those global solutions are asymptotic for large time to self-similar solutions of the single power nonlinear heat equation, i.e. with g ≡ 0.We emphasize that although equation (1.1) itself has no self-similar structure, it does have solutions which are asymptotically self-similar. Also, we are primarilywhere f is called the profile of the solution. The standard approach to studying self-similar solutions starts with the equation for the profile f obtained by substituting the self-similar ansatz into (1.2). Basic tools for studying the asymptotic behavior of solutions include the maximum and comparison principles, variational methods, and dynamical systems.In the case a = −1, where all solutions of (1.2) are global, we refer the reader to Gmira and Veron [11], Kamin and Peletier [13], Escobedo, Kavian and Matano [6], Galaktionov, Kurdyumov, and Samarskii [9] and Herraiz [12], as well as the references cited in these papers. While these papers contain a great wealth of information, we recall here only those results which have direct bearing on the present article. Assume that n(p 1 − 1)/2 > 1. Let ϕ ≥ 0 be such that 0 < lim |x|→∞ |x| α ϕ(x) = A < ∞ for some some α > 0, with