This report is the outcome of a meeting arranged to assess the options and need for co-operation of Nordic and Baltic authorities regarding safety of genetically modified organisms (GMOs), with the emphasis on environmental aspects. About 30 participants representing various authorities working with GMO issues in all Nordic and Baltic countries were present at the workshop. The issues of co-existence, risk assessment and monitoring were covered in the workshops of the meeting which served as a tool for exchanging information and experiences. The results were used as a basis for assessing the need for future co-operation and for formulating its putative forms. The report consists of an executive summary, introduction, reports from group discussions, and background information on the issues covered in the meeting. Description of the relevant authorities in each country is included.