Thyroid-hormone-dependent development of the neuroretina has principally been described in amphibia. Here, we show by in situ hybridisation that mRNAs coding for three distinct thyroid hormone receptors (TRs), TRα and two TRβ variants, are differentially expressed during chick retinal development. We isolated a cDNA for a novel N-terminal variant of chick TRβ (cTRβ) that is predominantly expressed in retinal development. Interestingly, in its N-terminal A/B domain cTRβ2 is 70% homologous to the rat pituitaryspecific TRβ. Expression of cTRβ mRNA was high at embryonic day 6 (Eli) in the retinal outer nuclear layer (ONL) and decreased to low levels at hatching. Mrna for the previously described chick β receptor, cTRβ0, was expressed at low levels in both the ONL and the inner nuclear layer (INL) after E10. In contrast, cTRa expression occurred in the ONL, INL and ganglion cell layer at intermediate and later stages. Finally, cTRβ2 confers a stronger irans-activation of reporter gene transcription than cTRβ0. The distinctive kinetics and localisation of TRa and β gene expression suggest cell- and stage-specific functions for TRs, both individually and in combinations, in chick neuroretinal development.