Background: Many varied activities are encompassed by the term "nutrition(al) surveillance". Several national surveillance systems were initiated soon after the World Food Conference in 1974, but few have lasted. Most were complex, expensive, slow to produce findings, and were eventually stopped. This paper discusses why nutrition surveillance in low-income countries is so hard to sustain, and identifies the key factors in systems which have been maintained. Discussion: For nutrition surveillance activities to be sustainable, there needs to be: demand for the information; a reasonable cost as well as a cost-efficient process; speedy generation and dissemination of good quality information; secure allocation of resources from the government and/or donor; and a central, organizing institution for strong coordination of data collection, analysis, interpretation and communication. Investment in local individual and institutional capacity plus the retention of experienced staff are important. A periodic evaluation of the process should be an integral part of surveillance activities. For national systems the ideal coordinating institution should sit within a government structure separate from those with direct involvement in health or agriculture, such as a ministry of planning, as those who lead the surveillance must be independent of decision-makers but need to understand and prioritise their needs for information. The findings need to be communicated clearly and the means of presentation adapted to different audiences. To promote participation, the findings should be shared with stakeholders at all levels. Summary: This review of the development of nutrition surveillance in low-income countries over the last 40 years finds that sustainability hinges on cost, capacity development, location of the institutional base, demand for the products, and participation. These considerations are noteworthy given the pivotal role of nutrition surveillance information in national and sub-national policy-making, planning and programming. Information from nutrition surveillance also provides an increasingly important mechanism to hold governments to account and to allow progress towards international targets to be tracked.