We characterized the expression pattern of the nuclear receptors liver X receptor (LXR) alpha and beta during mouse embryonic development and in adulthood by in situ hybridization experiments. LXRalpha and LXRbeta are detected in the liver starting at 11.5 days postcoitum. Later, LXRalpha expression remains high in organs involved in lipid homeostasis, such as liver, intestine, and brown adipose tissue, whereas LXRbeta is more ubiquitously expressed and enriched in tissues of neuronal and endocrine origin.