OICC Press Mathematical Analysis and its Contemporary Applications 3 1 2021 01 01 Stability of quartic functional equation in paranormed spaces 10.30495/maca.2021.1924046.1001 EN Subramani Karthikeyan Department of Mathematics, R.M.K. Engineering College, Kavaraipettai - 601206, Tamil Nadu, India Choonkil Park Research Institute for Natural Sciences, Hanyang University, Seoul 04763, Korea John Michael Rassias Pedagogical Department E.E., Section of Mathematics and Informatics, National and Capodistrian University of Athens, 4 Agamemnonos Street, Aghia Paraskevi, Athens 15342, Greece Journal Article 2021 01 01 In this paper, we prove the Ulam-Hyers stability of the following quartic functional equation f x + y -2z 2 + f y + z -2x 2 + f z + x -2y 2 = 9 16 (f(x -y) + f(y -z) + f(z -x)) in paranormed spaces using both direct and fixed point methods.