The Paley-Wiener space P W (G) on a stratified Lie group G is defined via the spectral decomposition of the associated sub-Laplacian. In this paper, we show that functions in P W (H), where H denotes the Heisenberg group, extend to an entire function on the complexification H C , satisfying a growth estimate of exponential order two. We also show that a converse, characterizing elements of P W (H) only in terms of pointwise growth behaviour of the entire extension, is not available.