Condition in the tortoise Testudo hermanni was assessed using the ratio of observed mass (M) to that predicted (M') from the allometric relationship M=aL^b, where L is body length. A condition index (CI) was based on regressions of log M on log L in July (taken as a standard); these regressions differed significantly between females and males. The CI log M/M' was slightly left-skewed, but was preferred to the simple ratio M/M' for ease of analysis of interaction effects. Log M/M' ranged from approximately -0.1 to +0.1 in the wild, equivalent to observed mass of 80-120% of predicted mass. Condition varied seasonally, being low after emergence from hibernation, maximal in spring (April to June), and decreasing in autumn. The detailed pattern of seasonal variation differed significantly between adult females, adult males, and subadults. Regression equations for log M on log L in different months are provided for a seasonally-adjusted condition index (CI_s), to assess the relative condition of individuals and annual samples measured in different months.

Key words: allometry, condition index, season, Testudo, tortoise