Urine deposit smears of 58 patients with urinary schistosomiasis, 20 with acute glomerulonephritis, and 14 with urinary stones were stained with Hansel's stain. Eosinophiluria was seen in all cases of urinary schistosomiasis (median 0.73 [73%] of urinary white blood cells [WBCs]); 13 (65%) of those with acute glomerulonephritis (median 0.03 [3%] of urinary WBCs); and 2 (14%) patients with urinary stones (0.01 [1%] and 0.05 [5%] of urinary WBCs). Other features included the presence of ova and activated macrophages and giant cells in urinary schistosomiasis, an increased number of mononuclear cells and stained cellular casts in acute glomerulonephritis, and an increased number of neutrophils in urinary stones. In schistosomiasis, urine differential leukocyte counts were unrelated to those of the blood. Moreover, urine eosinophil percentages were always higher than those in the blood. Thus, in urinary schistosomiasis, eosinophiluria could be explained by exudation, sloughing of granulomata, as well as bleeding from the urinary tract surface. Electron microscopic examination confirmed that most of the leukocytes were eosinophils. Some of these were adherent and degranulating over ova with variable miracidial damage. Urine eosinophil and egg counts were not correlated to each other. Staining urine deposit smears, with the use of Hansel's stain, is useful in the investigaton of hematuria. Heavy eosinophiluria and few mononuclear cells favor the diagnosis of urinary schistosomiasis rather than acute glomerulonephritis or urinary stones. These results diminish the value of eosiniphiluria as corroborative evidence of drug-induced interstitial nephritis in areas of endemic urinary schistosomiasis.