With the increase of design complexities and the decrease of minimal feature sizes, IP reuse is becoming a common practice while crosstalk is becoming a critical issue that must be considered. This paper presents two macro-models for specifying the timing behaviors of combinational hard IP blocks with crosstalk effects. The gray-box model keeps a coupling graph and lists the conditions on relative input arrival time combinations for couplings not to take effect. The black-box model stores the output response windows for a basic set of relative input arrival time combinations, and computes the output arrival time for any given input arrival time combination through the union of some combinations in the basic set. Both macro-models are conservative, and can greatly reduce the pessimism existing in the conventional “pin-to-pin” model. This is the first work to deal with timing macromodeling of combinational hard IP blocks with the consideration of crosstalk effects.