The realisation criteria of continuous-lime current-mode (CM) active filters for low frequency operation are investigated. New lossless and lossy integrators for low frequency operation using dual-output current conveyors (DIO-CCII) are proposed. Basing on these building blocks, a CM universal filter with low natural frequencies suitable for integrated circuit implementation is presented. Using the proposed filter, natural frequencies as low as a few ten hertz can be achieved on an integrated circuit chip without using any external passive components. The proposed circuit simultaneously produces three basic filter responses at its high impedance outputs and it has good passive and active sensitivity performance.