Annular hollow fibres were prepared by co-extrusion of two different polymer solutions through a triple orifice spinneret. PVDF/NMP/PEG200 and PESf/PVP/NMP/EgOH were used as inner and outer dope solutions, respectively. Experimental conditions on the formation of annular hollow fibres were studied experimentally. Structures of the annular hollow fibres were examined by SEM. Through the proper selection of dope composition and spinning parameters, the annular hollow fibre membranes could be formed with controlled width of the hollow fibre annulus. Both inner and enter layers of the annular hollow fibre possess open ended finger-like cavities facing to the annulus with its mouth diameters of about 20 mum. The immobilization of yeast in the annular passages of the hollow fibre prepared was also studied by SEM. The results show that the yeast could successfully be immobilized in the cavities of the inner layer and grew to very high densities throughout the annular passages.