Despite a widely recognised need, most countries still have no coherent system to deal with scientific misconduct. Committees have been established by the national medical research councils in Denmark (1992), Norway (1994), and Sweden (1997), and by the Ministry of Education in Finland (1994), to deal with scientific misconduct--ie, to initiate preventive measures, to investigate alleged cases, or both. Each committee includes both scientifically and legally qualified members. The employing institutions are responsible for possible sanctions or punishments. So far, 47 cases have been accepted for investigation, the majority (25) being Danish. Disputed authorship was the most frequent reason for investigation. Junior researchers made complaints in only three of the investigated cases. Investigations have been completed in 37 cases; in nine cases, dishonesty was revealed--two of them were related to the same researchers. Cooperation between the four Nordic committees has shown close agreement on specific issues and cases, despite minor differences in definitions, organisation, and procedures.