Worldwide there are an estimated 1.5 billion episodes of diarrhoea each year. Diarrhoeal illness is the second leading cause of death in children under five and claimed more than 1.4 million lives in 2000.(1) In developed nations few people die from diarrhoeal diseases but it is an important cause of illness that carries a substantial health-care cost. Routine faecal culture is labour intensive and expensive with low isolation yield.(2) Costs could be reduced by using a selective approach to faecal culture. There are few reliable, non-invasive diagnostic tools that are used as biological markers for inflammatory colitis. Feacal leukocyte examination has been used, however it needs prompt microscopic examination, is not standardised, has poor sensitivity and is limited by the experience of the technician.(3) Extended transport delays result in degredation of leukocytes while some enteric pathogens, such as Clostridium difficile, produce toxins that lyse leukocytes.(4,5) In this study, a simple method was developed using Leukocyte esterase as a marker for inflammatory colitis. Leucocyte esterase has been used for semi-quantitation of leukocytes in urine for many years.(6) Of 531 patients tested in the study 192 (36%) were positive for Leukocyte esterase and only 125 specimens had WBC seen. Of the 192 specimens, 59 had an isolate identified that would cause an inflammatory response. There were 60 specimens where Leukocyte esterase was detected but microscopy was negative for WBC and an inflammatory cause was not isolated. In a smaller sub-study, Lactoferrin testing was performed on this Leucocyte esterase positive, microscopy negative cohort to confirm the presence of WBC. Lactoferrin was present in 88% of these specimens. While lactoferrin is an accepted inflammatory marker(4) with commercial kits available, at $21 a test it is expensive compared to 46 cents per Leukocyte esterase test. Leukcocyte esterase is stable and provides a screening tool accesable to any country in the world for the battle against identifying and treating inflammatory diarrehoea illness globally.