Present study was carried out with the aim of investigating the effect of ascorbic acid supplementation and altered dietary protein level on the rectal temperature, haematocrit value and blood ascorbic acid status of rats exposed to chronic and acute heat stress. It was observed that the normal rectal temperature of adequately (18%) protein fed rats was quite higher (37.41 ± 0.12⁰C) than that of the protein restricted (6%) rats (36.65 ± 0.12⁰C) which was observed to be further augmented by the prior supplementation of ascorbic acid. It was further observed that the stabilizing tendency of rectal temperature took more than 3 days of heat exposure when rats were under protein restriction. Decrease in haematocrit value after chronic heat exposure and an increase in it in acute heat-exposure were observed. Haematocrit values of both control and treated groups of animals were also observed went down to a great extent as a result of protein restriction. Plasma ascorbic acid level was observed to be increased after acute heat exposure in 18% as well as 6% protein-fed rats and after chronic heat exposure in 6% protein-fed rats. But, when the ascorbic acid content was estimated in erythrocytes it was found to be diminished after acute heat exposure in protein-restricted rats only.