The benefits of crop protection products have to be balanced against the risks to farmers and other agricultural workers handling and applying them. The extent of acute pesticide poisoning in these workers, particularly in less developed countries, has often been based on inadequate information. A number of approaches have been taken by researchers to acquire information on pesticide poisoning. These have resulted in worldwide (global) estimates and regional, localised or field assessments. The methods include descriptive epidemiology, cross-sectional and case studies. Attempts to estimate global pesticide poisonings have often been based upon extrapolations and assumptions from chemical-related fatalities in a small number of countries; such estimates do not provide reliable data. Epidemiological studies, relying mainly on hospital and poison centre data, have been biased towards the more severe poisonings, whereas field studies indicate that occupational pesticide poisoning is associated with less severe and minor effects. Many reports do not adequately distinguish between intentional, accidental and occupational pesticide poisoning statistics or are dominated by cases of intentional (suicidal) poisoning which, by their nature, result in severe or fatal results. The majority of reports do not adequately describe whether individual cases are minor, moderate or severe poisonings. In order to assess information on acute pesticide poisoning in agricultural workers in less developed countries and to draw conclusions on the extent and severity of occupational poisoning, the most recent (post-1990) literature was reviewed. Data were also derived from the World Health Organization (WHO), United Nations Environment Programme (UNEP) and the International Labour Office (ILO). The collected information was analysed to assess the extent and severity of occupational acute pesticide poisoning in less developed countries. Occupational acute pesticide poisonings in these countries are a small proportion of overall reported poisoning and are associated with the more minor effects of pesticides. They are a small proportion (<1-4%) of the several million cases of occupational injuries and ill health in agricultural workers worldwide. However, improvements are required for the collection of acute pesticide poisoning data in less developed countries and in the verification of the circumstances of poisonings and their relative severity. There is the need to move away from further attempts to estimate global data and concentrate instead on obtaining reliable data from realistic crop protection activities.