The cholinergic neuronal differentiation factor (CDF)/leukemia inhibitory factor (LIF) promotes survival and/or differentiation of specific neuronal populations in vitro. To investigate the spatial and temporal distribution of CDF/LIF binding sites in the developing rat nervous system, we localized binding of iodinated native rat CDF/LIF by radioautography. We find that specific CDF/LIF binding sites are present in distinct regions of the nervous system at defined developmental stages. CDF/LIF binding is detectable in all sensory ganglia examined, both neural crest- and placode-derived, and in all sympathetic and parasympathetic ganglia examined. In the central nervous system, in contrast, binding is restricted to specific regions in the motor, sensory, and limbic systems. These in vivo results not only support culture studies which suggest CDF/LIF involvement in development of specific populations of neurons, but also suggest new roles played by CDF/LIF.