Photonic crystal fibres with large mode areas are widely employed for reducing the impairments arising from various nonlinear effects. We suggest a new design of photonic crystal fibres with large effective mode area. The fibre consists of six air-hole rings with two different structures and unequal diameters, where the air holes of the third ring are filled with the substance having high refractive index. Employing a full vectorial finite-element method, we have found that our structure exhibits a large effective mode area (up to 3575 µm 2 at the light wavelength of 1200 nm) and low confinement losses (about 5.70×10-3 dB/km at 1550 nm).