Thyroid hormones (THs) are critical for the growth, development and homeostasis of many organisms and are necessary for metamorphosis of Xenopus laevis tadpoles. TH-induced metamorphosis requires alterations in the transcriptome and the proteome. However, only a few of the molecular components of this developmental program have been identified and their interrelationship remains unclear. Using a cDNA array comprised of 420 known anuran genes and quantitative polymerase chain reaction, we have identified 93 TH-responsive genes in the tail of premetamorphic tadpoles after exogenous administration of 3,3', 5-triiodothyronine (T₃). Fifty-three of these mRNA transcripts have not previously been characterized as TH-responsive in any species. The gene expression profiles show distinctive temporal patterns with most transcript steady state levels increasing after induction of metamorphosis. Two-dimensional gel electrophoresis of total protein extracts from the tail shows changes in steady state levels of many proteins after T₃ treatment. Of the up-regulated proteins, ten were identified by peptide mass mapping. These data identify potential components involved in the regulation of Xenopus tail regression by T₃ and begin to address a critical question regarding the interrelationship between the transcriptome and the proteome in TH-dependent developmental processes.