The National Egyptian Thyroid Screening Program has been established for years but the definition of optimal ranges for thyroid hormones in preterms related to gestation & postnatal age has not been established. Our prospective study including 100 preterms, 27-36 weeks gestation admitted in NICU. All thyroid functions were done from day 3-7 using RIA. Results: in preterms mean ±SD for FT3, FT4 & TSH were 2.7±0.7 Pg/ml, 1.5±0.4 ng% & 3.8±3.2uU/ml respectively. There is relation between low FT4 & bad clinical status& between low FT3 & poor outcome.