The cost effectiveness of several modes of family planning service delivery based on the cost per couple-year of protection (CYP), including commodity costs, is assessed for 1991–92 using programme and project data from fourteen developing countries (five in Africa, four in Asia, three in Latin America and two in the Middle East). More than 100 million CYP were provided through these family planning services during the 12 months studied. Sterilisation services provided both the highest volume (over 60% of total) and the lowest cost per CYP ($1.85). Social marketing programmes (CSM), delivering almost 9 million CYPs, had the next lowest cost per CYP on average ($2.14). Clinic-based services excluding sterilisation had an average cost of $6.10. The highest costs were for community-based distribution projects (0·7 million CYPs), which averaged $9.93, and clinic-based services with a community-based distribution component (almost 6 million CYPs), at a cost of $14.00 per CYP. Based on a weighted average, costs were lowest in the Middle East ($3.37 per CYP for all modes of delivery combined) and highest in Africa ($11.20).