AbstractDRG11 is a paired domain transcription factor that is necessary for the assembly of the nociceptive circuitry in the spinal cord dorsal horn. It is expressed in small dorsal root ganglion (DRG) neurons and in their projection area in the spinal cord. Drg11 knockout mice exhibit structural and neurochemical defects both at the DRG and spinal superficial dorsal horn and present reduced nociceptive responses. In this study, a polyclonal antibody against DRG11 was generated and used for a detailed systematic spatio‐temporal analysis of DRG11 expression during development. DRG11 is first detected at E10.5 in the spinal dorsal horn, DRG and trigeminal ganglion, where it persists until P14‐21. At the cranial level, DRG11 expression is observed from E10.5 up to the same early post‐natal ages in several cranial sensory ganglia and brain nuclei. These results suggest that DRG11 is required for the establishment of the first neuronal sensory relay along development. Developmental Dynamics 236:2653–2660, 2007. © 2007 Wiley‐Liss, Inc.