This study investigated the feasibility and validity of using non-invasively collected ice urine samples to measure cortisol concentrations in Weddell seals. Radio-immunoassays were used to determine urinary cortisol, and spectrophotometric assay was used to determine creatinine concentrations. This allowed for urinary cortisol/creatinine ratios (UCCR) to be compared between pure urine and urine collected from the ice. Urinary cortisol/creatinine ratios values of ice urine proved an effective method of studying cortisol concentrations in Weddell seals as there was no difference between pure urine and ice urine UCCR values. There were no inter-sexual or age-related differences in UCCR values in either pure or ice urine. Zoo Biol 0:1–8, 2006. © 2006 Wiley-Liss, Inc.