The nucleus 198Pb was populated via the 186W(17O,5n)198Pb reaction at beam energies of 92 and 98 MeV. A highly regular rotational ΔI=1 band has been found. Angular correlation measurements confirm the transitions to be dipoles. Assuming M1 multipolarity for these transitions the experimental data are interpreted in terms of a configuration of oblate shape. This is the first such collective oblate structure identified in the A∼200 mass region.