To obtain information that could assist the clinician to differentiate between shigellosis and amoebic dysentery, we compared clinical features and stool findings in 58 adult male patients in Bangladesh. Mean values indicated that patients with invasive amoebiasis were older and had a longer prehospital illness, a lower body weight, less frequent fever, a lower haematocrit and a higher white blood cell count than patients with shigellosis. The mean number of faecal leucocytes per mm3 was significantly higher in shigellosis than in amoebiasis (28,700 vs 10,300) and correlated with the estimated number of faecal leucocytes per microscopic high power field in a wet mount preparation. Patients with shigellosis more often had over 50 white blood cells per high power field. Although the mean stool pH in amoebiasis was lower than in shigellosis (6.26 vs 6.60), the difference was not statistically significant. Concentrations of stool electrolytes did not differ between the two diseases. These findings indicate that age, duration of illness, the presence of fever and the number of faecal leucocytes may help to differentiate between shigellosis and amoebic dysentery.