A disinfectant cap for sterile liquid dispensers is disclosed. The cap includes a biocide-containing reservoir separated from the hollow interior of the cap by a rigid partition having an aperture therein for receiving the outlet port of the dispensing end of the dispenser, the cap being configured such that when in a closed configuration, the outlet port of the dispensing end extends through the aperture into the biocide-containing reservoir and the rigid partition is configured such that when the cap is removed from the dispensing end the biocide is retained in the reservoir. This may be achieved by selecting the size of the aperture such that when the cap is removed from the dispensing end the biocide is retained in the reservoir by surface tension. Or the partition may be provided with a hinged flap which seals the aperture when the cap is removed from the dispensing end and which is moved away from the aperture when the outlet port extends through the aperture.