This paper considers the problem of attitude and altitude control of quadrotors using the sliding mode control theory. The mathematical model of the quadrotor is derived using the Euler-Newton formalism with extended assumptions on disturbing aerodynamical forces (not necessary uniformly bounded). The proposed control demonstrates an enhanced robustness against such disturbances. The comparison between the classical controller and the proposed one is demonstrated analytically, through Lyapunov theory, and in simulations to validate the proposed sliding mode control algorithm.