A new class of (nonlinear) operators of monotone type is introduced: a mapping T from the real Banach space X into the set 2^X* of all subsets of the conjugate space X^* is said to be generalized pseudo-monotone if for any sequence {u_j} in the effective domain of T with u_ju in X and any corresponding sequence w_jw in X^*, w_j ε Tu_j, for which lim sup(w_j − w, u_j − u) 0, it follows that w ε Tu and (w_j, u_j) → (w, u). It is shown that most of the known mappings of monotone type are generalized pseudo-monotone, as, for example, maximal monotone and pseudo-monotone mappings. The class of generalized pseudo-monotone mappings is then investigated in detail. An important part of that study is devoted to the discussion of the range of a generalized pseudo-monotone mapping.