Two populations of neurones can be distinguished in sections of dorsal root ganglia (DRG) by light microscopy and immunofluorescence techniques: large light (neurofilament-positive) and small dark (neurofilament-negative) neurones. This paper shows that corresponding populations can be seen in cultures of adult rat DRG, as judged by cell body size distributions and neurofilament content. None of the large light neurones, which are strongly positive for neurofilament immunoreactivity, show capsaicin sensitivity, which is detected histochemically by a cobalt uptake stain.