<jats:title>SUMMARY</jats:title><jats:p>Urinary 3,5‐diiodotyrosine (DIT) and thyronine (T0) excretion was investigated in 18 patients with chronic renal disease. In accord with previous findings serum T4 and thyroid hormone binding proteins measured in 17 patients were in the low or normal range. Urinary albumin excretion was elevated in all 18 and T4 binding prealbumin (TBPA) in 15 of the 18. Urinary T0 excretion measured in 12 patients was also significantly lower than normal (mean±SD 4.4±2.6 vs 15.8±5.8 nmol/24 h renal vs normal 2 <jats:italic>P</jats:italic><0.001). In contrast urinary DIT excretion was significantly elevated in renal patients compared with normal subjects (2.0±1.5 vs 0.75±0.41 nmol/24 h, respectively). Possible sources of the increased DIT are discussed.