Nuclear receptors are members of a superfamily of ligand-inducible transcription factors involved in the regulation of biological processes as diverse as metabolism, development and reproduction. They mediate the transcriptional response to hormones such as the sex steroids (progestins, estrogens and androgens), adrenal steroids (glucocorticoids and mineralocorticoids), vitamin D3, thyroid and retinoid (9-cis and all-trans) hormones, in addition to a variety of metabolic ligands. They are modular proteins that contain two main domains, the DNA binding domain (DBD) and the ligand biding domain (LBD). At present time, no high resolution structures were resolved which contain both domains. Previously, our laboratory published the low resolution structures for a member of the superfamily with both domains, RXRDLα. Similarly, studies are in progress to solve the low resolution structure of TRDLα1, as well as TRDLb1 in the presence or not of T3. From SAXS measurements TRDLα1 appears to be in a dimeric form in solution at concentrations of 3 and 8 mg/ml, TRDLb1 showed to be tetrameric without T3 and dimeric in the presence of T3 also at concentrations of 3 and 8 mg/ml in both cases. SAXS studies also were releases with TR DBD b in the presence and absence of DNA responsive element F2.