The enteric nervous system (ENS) is a complex network of neurons in the gut, regulating many local, vital functions of the gastro-intestinal tract. The ENS is also part of the bidirectional gut-brain axis. The murine immorto fetal enteric neuronal (IM-FEN) cell line was chosen as a model to study enteric neurons. This cell line can be differentiated into cells with a neuronal phenotype, although they do not produce action potentials in vitro. It was concluded that the differentiation process in our laboratory was successful, based on positive staining for neuronal proteins. Proliferating IM-FEN cells have an unstable growth rate in our laboratory. An indicator of growth rate was calculated, and this indicator was found to be related to seeding density and number of days in culture, and was unrelated to person culturing, previous overconfluency or passage number. The indicator of growth rate was also unrelated to successful use of differentiated cells in follow-up experiments. We recommend the following conditions for optimal culture of IM-FEN cells. Keep cells in culture until 80 % confluent before passaging, seed cells at a density of 0.0133 million cells per cm(2), and anticipate on unstable growth rates and the risk for overconfluency.