Parreira J. R., Bolina O., Perez J. F. Neel Order in the Ground State of Heisenberg Antiferromagnetic chains with Long Range Interactions (15K, LaTeX) ABSTRACT. We consider the ground state of one-dimensional antiferromagnets with long range interactions with Hamiltonian given by $$ H=\sum_{x} \sum_{n} (-1)^{n} J(n) {\bf S}_{x}.{\bf S}_{x+n} $$ where $J(n)=n^{-\alpha}$, with $J>0$. We prove N\'eel order for all $1<\alpha<3$ if the spins $s$ is sufficiently large. We also prove the absence of long range order when $\alpha>3$ for any spin value.