Monitoring glucocorticoids is commonly used to evaluate heightened physiological demands on a population under varying conditions. However, detecting changes depends on knowing baseline and temporal patterns in glucocorticoids. Plasma corticosterone was measured in the Turks and Caicos iguana (Cyclura carinata carinata) to determine diurnal and bi-annual baseline patterns as part of monitoring associated with a large-scale translocation program. Plasma from wild males (N = 100) and females (N = 96) was obtained in January of 2002 and 2003 and June 2002. Glucocorticoid concentrations were determined by radioimmunoassay (RIA). Glucocorticoid levels were significantly greater in females than males, and showed a tendency to be inversely related to body condition in females but not in males. For the January samples, there was a non-significant trend for glucocorticoid levels to be highest in the morning. Establishing a daily pattern for only the hours the animals are above ground is useful for evaluating subsequent field studies. The potential influence of reproductive state and seasonal rainfall patterns on glucocorticoid levels is discussed.