The neutron deficient Asimilar to90 nuclei constitute a good testing ground for shell model approaches based on spherical or deformed basis. New experimental data are presented for the Ru-90 nucleus, as obtained with the reaction Ca-40+Ni-58 at 135 MeV. The yrast band has been extended to higher spin states and a new band, tentatively assigned as a negative parity band, has been identified. The observed structures are compared with predictions of the projected shell model, which uses a deformed basis. Possibility of the occurrence of low-lying high- K states in this nucleus is discussed.