The full experimental evidence of fine structure in disordered superlattices is reported. The experimental results agree with the numerical predictions, thus indicating that this effect is related to residual coupling between adjacent identical wells in the case of Anderson localization. This feature indicates an intrinsic difference between disorder-induced and electric-field induced localization, where no spectral fine structure can be observed in the strong localization limit. Copyright (C) 1996 Elsevier Science Ltd