Predictions　of　the　operating　liquid　level　in　the　evaporator　of　a　closed　two-phase　thermosyphon　(gravity　heat　pipe)　are　given　throughout　a　simplified　analysis　which　takes　the　influence　of　the　dimension　and　condensation　heat　transfer　in　the　condenser　of　the　heat　pipe　into　account.　In　order　to　verify　the　accuracy　of　our　model　comparison　of　the　present　study　with　some　published　results　is　made　by　means　of　computational　examples.