This note responds to the request by SBSTA for information on existing national systems for preparing greenhouse gas inventories. This information is intended to assist Parties in considering how to design guidelines for national systems under Article 5.1 of the Kyoto Protocol. The note summarizes information on the current practices in some Annex I Parties and identifies issues relevant to the existing national systems for the preparation of greenhouse gas inventories, including timing and frequency of submission of these inventories. The main findings of this paper were presented during the workshop on national systems and issues relating to adjustments, which was held in Bonn from 14 to 16 March 2000