Signaling pathways mediated by receptor tyrosine kinases (RTKs) are under positive and negative regulation, and misregulation of RTK signaling results in developmental defects and malignancy. A major class of antagonists of Fgf and Egf signaling are the Sprouty proteins. Through an enhancer detection approach, we isolated the sprouty1 (spry1) gene, expressed in multiple developing organs during embryogenesis. We analyzed expression of spry1 between tail bud stage and 10 days postfertilization. From the tail bud stage on, transcript and reporter are detected in the craniofacial region and in the mid–hindbrain boundary, where expression persists until adulthood. Further expression domains are the telencephalon, hindbrain, dorsal diencephalon and epiphysis, branchial arches, pituitary, and the tubular gill epithelium. In the trunk spry1 is also prominently expressed in pronephros, the lateral line and tail fin. Sprouty1 acts in Fgf signaling downstream of Fgfr1, as its expression is abrogated through the small molecule inhibitor of this receptor, SU5402. Developmental Dynamics 237:2594–2603, 2008. © 2008 Wiley-Liss, Inc.