[en] Low-temperature heat-capacity, electrical resistivity, and magnetization measurements are performed to investigate the superconducting and magnetic behavior of ErBa₂Cu₃O/sub 7-//sub x/. This compound exhibits a superconducting transition at 84 K as determined from zero resistance and Meissner effect. A well-defined magnetic transition is seen at 0.87 K from heat-capacity measurements. We deduce the coexistence of superconductivity and antiferromagnetic order in this compound; however, magnetization data show that the paramagnetism from Er/sup 3+/ and superconductivity are independent, leading to indirect evidence of extremely anisotropic superconductivity in this class of compounds