An analysis of waves and instabilities in the recently created pair-ion plasma is presented. The pair-ions, C-60(+/-), have the same mass and opposite charge. In the case of an unmagnetized pair-ion plasma only two wave modes exist, namely the electrostatic Langmuir mode and the electromagnetic transverse mode. In the case of a magnetized pair-ion plasma containing electrons, the linear and nonlinear drift modes are presented. In addition, the instabilities of the two stream and the shear flow gradient type are discussed.