ADAMTS1/METH1 belongs to the ADAMTS (a disintegrin and metalloprotease with thrombospondin repeats) family of proteins that currently comprises 18 members. Targeted inactivation of the ADAMTS1 gene results in morphological defects in the kidney, adrenal gland, and adipose tissue in addition to growth retardation and infertility in females. To gain further insight on the biology of ADAMTS1, we examined its expression pattern in the developing mouse from embryonic day 10 (E10) to E18. Expression analysis by RNase protection assays revealed detectable levels of ADAMTS1 transcripts in E10-E18 yolk sac, placenta, brain, heart, lung, limb bud, liver, spleen, and kidney, with much lower levels in the adult. Using in situ hybridization, we have localized ADAMTS1 transcripts predominantly to the epithelium of the developing lung, pancreas, kidney and to a subset of neurons in a temporally restricted manner. Expression was also detected in the tunica media of the aorta, pulmonary, and hepatic vessels.