We generalize the classical Schur's test to the boundedness of integral operators from L p to L q spaces equipped with possibly different measures, for 1 ≤ p ≤ q < ∞. As an application, we determine exactly when a class of integral operators are bounded from L p (Bn, dvα) to L q (Bn, dv β ), where 1 ≤ p ≤ q < ∞, Bn is the unit ball of n-dimensional complex Euclidean space C n , and dvα and dv β are weighted area measures on C n . The result generalizes a result by Kures and Zhu.