The survival of parasitic plant Rafflesia depends on the host plant, habitat condition, vegetational types, , pollination and the dispersal of seeds. This study aims to investigate visits by insects and variation in floral temperatures of Rafflesia gradutensis during flowering. The flower was observed to be visited by green fly Lucilia sericata and weaver ant Oecophylla sp. The number of visits L. sericata was 617 times and 337 times by Oecophylla sp, in which most of the visits occur during mid-day. The average observed highest surface temperatures of were 28.40C (perigone) and 28.70C (diaphragm), which were slightly above the air temperature of 27.80C. The temperature experiences a gradual increase from the morning till the noon, and then it decreased toward late afternoon. The results of the floral temperatures indicate endothermy in R. gradutensis. However, thermo-regulation related to endothermy needs further investigation.