The analysis of mass and energy budgets provides critical insight for the modeling of both individual organisms and populations. Ectotherms in particular are closely tied to environmental variation because of thermal dependence of most physiological functions. We studied the effects of temperature on digestion and growth in 28 Timber Rattlesnakes (Crotalus horridus) from Arkansas, Mississippi, and Virginia. We conducted feeding trials in environmental chambers in a repeated-measures design to analyze the effects of three trial temperatures (20, 25, and 30°C) on digestion and growth. We found no significant temperature effect on passage times (average 12.36 days), apparent digestibility (average 87.5%), or metabolizable energy (average 80.6%) across the 10°C temperature range. There was an apparent temperature-dependent tradeoff in the allocation of mass and energy to growth in girth versus growth in length. Snakes allocated similarly to body mass at all three temperatures; however, growth in SVL increased significantly from 20°C to 30°C. These observations suggest that snakes at 20°C allocated to increases in girth, whereas snakes at 25°C and 30°C allocated increasingly to increases in body length. We estimated the metabolic cost of growth to be approximately 10.5 kJ g⁻¹ dry mass (95 % CI: 6.8–14.1 kJ g⁻¹ dry mass), which corresponds well with previous estimates in ectotherms.