Primary cell cultures are useful for studying the function of neurons in a simplified and controlled environment. We established a primary culture of antennal cells from pupal blowflies in order to investigate olfactory receptor neurons. In cultures, neuron-like cells were identified on the basis of morphology and immunocytochemical characterization with anti-HRP staining. Neuron-like cells showed variety in the extension pattern of neurites. Many neuron-like cells extended a single prominent long process, which reached about 200 microm after four days, and several short ones. However, some neuron-like cells differentiated in other ways; some exhibited bipolar or multipolar processes, distinct from intact olfactory receptor neurons. The size of cell bodies of neuron-like cells as divisible into two groups; approx. 7 microm diameter and 10-15 microm diameter. Neuron-like cells in culture will provide a good model for electrophysiological analysis and for developmental studies of olfactory receptor neurons.