  In this work, we study the existence and uniqueness of bounded Weyl almost
periodic solution to the abstract differential equation u ' (t) = Au(t) + f
(t), t $\in$ R, in a Banach space X, where A : D (A) $\subset$ X $\rightarrow$
X is a linear operator (unbounded) which generates an exponentially stable C
0-semigroup on X and f : R $\rightarrow$ X is a Weyl almost periodic function.
We also investigate the nonautonomous case.
