Consider the Laguerre functionslpn(t)=(−1)n2p−−√Ln(2pt)e−pt (with parameterp>0), where theLn are the Laguerre polynomials with parameter α=0.{lnp (t)} n=0∞ forms a complete orthonormal system inL2 ([0, ∞)). A well known and often used property of the Laguerre functions is the convolution property:2p−−√lpi∗lpj=lpi+j+lpi+j+1 for alli,j≥0. It is the objectiveof this note that the system of Laguerre functions is the only complete and orthonormal system ofL2 ([0, ∞)) satisfying the convolution property.