The dependence of Andreev reflection on the heavy-fermion superconductor UPt3 on surface conditions has been investigated by means of point-contact spectroscopy. In contrast to conventional superconductors the surface is expected to play a crucial role for unconventional superconductors like UPt3. The result supports that superconductivity in UPt3 can be described by a two-dimensional order parameter with point and line nodes.