Water relations and desiccation tolerance of adults of five species of heliconiine butterflies were examined in laboratory studies. Percentage of total body water ranged from 63.25% in female Dryas iulia F. to 67.8% in male Heliconius charitonius L.; water content of females was less than that for males in all five species. Male and female H. hecale Hewitson and D. iulia had lower percentages of total body water than the other species and sexes. Cuticular permeability ranged from 30.71 ± 2.21 μg cm⁻²h⁻¹ mmHg⁻¹ in female D. iulia to 50.1 ± 15.5 μg cm⁻²h⁻¹mmHg⁻¹ in female H. charitonius using Meeh’s formula to estimate body surface area. Actual surface area measurements of butterflies were 12–15 times greater for a given body mass than surface areas calculated from Meeh’s formula. Mortality of butterflies exposed to 30°C and 0–2% RH ranged from 15% (female H. melpomene rosina Boisduval and H. hecale) to 60% (male H. cydno Bates). Time of death varied between 8.67 ± 2.0 h in male D. iulia and 11.3 ± 1.55 h in female H. hecale; percentage of total body water lost at time of death ranged from 30.97% in male H. charitonius to 39.45% in female H. cydno. Percentage of initial mass lost and percentage of total body water lost increased as a power function with desiccation time. The implications of water loss and desiccation tolerance to butterfly exhibits are discussed.