Aims/hypothesis. The aim of this study was to examine the possible link between isolated post-challenge hyperglycaemia (2-h post-challenge plasma glucose ≥ 11.1 mmol/l, and fasting plasma glucose < 7.0 mmol/l) and mortality. Methods. The data from three population based longitudinal studies (in Mauritius, Fiji and Nauru) were pooled and mortality rates were determined in 9179 people who were followed for between 5 and 12 years. Results. There were 595 people with previously diagnosed diabetes, and 799 with newly diagnosed diabetes, of whom 243 (31) had isolated post-challenge hyperglycaemia. In comparison with people without diabetes, people with isolated post-challenge hyperglycaemia had an increased risk of all-cause mortality [Cox proportional hazards ratio (95 % CI): 2.7 (1.8–3.9) – men; 2.0 (1.3–3.3) – women], and of cardiovascular mortality [2.3 (1.2–4.2) – men; 2.6 (1.3–5.1) – women]. In addition, men with isolated post-challenge hyperglycaemia had a high risk of cancer death [8.0 (3.6–17.9)]. Conclusion/interpretation. These data show that isolated post-challenge hyperglycaemia, which can only be identified by the 2-h glucose, is common, and at least doubles the mortality risk. This should be considered in the design of screening programmes that use only fasting glucose [Diabetologia (1999) 42: 1050–1054]