Adhesion and patterning of cortical neurons was investigated on isolated islands of neuron-adhesive polyethylenimine (PEI) surrounded by a neuron-repellent fluorocarbon (FC) layer. In addition, the development of fasciculated neurites between the PEI-coated areas was studied over a time period of 15 days. The patterns consisted of PEI-coated wells (diameter 150 /spl mu/m, depth 0.5 /spl mu/m) which were etched in a coating of fluorocarbon (FC) on top of polyimide (PI) coated glass. The separation distance between the PEI-coated wells were varied between 10 and 90 /spl mu/m. This paper shows that chemical patterns of PEI and FC result in highly compliant patterns of adhering cortical neurons after 1 day in vitro. Interconnecting neurite fascicles between PEI-coated wells were especially present on patterns with a separation distance of 10 /spl mu/m after 8 days in vitro. A significant lower number of interconnecting neurite fascicles was observed on 20 /spl mu/m separated patterns. Effective isolation of neurons into PEI-coated wells was achieved on patterns with a separation distance of 80 /spl mu/m as no interconnecting neurite fascicles were observed.