In geometry, the elongated pentagonal orthobirotunda is one of the Johnson solids (J_42). Its Conway polyhedron notation is at5jP5. As the name suggests, it can be constructed by elongating a pentagonal orthobirotunda (J_34) by inserting a decagonal prism between its congruent halves. Rotating one of the pentagonal rotundae (J_6) through 36 degrees before inserting the prism yields the elongated pentagonal gyrobirotunda (J_43).