If 

 are two noises (stochastic processes), 

 and 

 are functions describing the action of two instantaneous nonlinear devices, we say that the 

 cross-correlation property holds in case the cross-correlation of 

 with 

 is proportional to the cross-correlation of 

 with 

 , whenever 

 and 

 are polynomials of degrees not exceeding 

 and 

 , respectively. We take 

 or 

 to mean that 

 or 

 is any continuous function. The Barrett-Lampard expansion 

 of the second-order joint density of 

 and 

 is used to derive an expression for the cross-correlation of 

 and 

 . This expression yields necessary and sufficient conditions for the validity of the cross-correlation property in three cases: 

 and 

 stationary, 

 unrestricted; 

 stationary, 

 unrestricted; 

 stationary, 

 . Examples are constructed with the help of special orthonormal polynomials illustrating the necessity and sufficiency of the conditions.