Abstract:Aim To determine the association of chronic diarrhea with intestinal aerobic predominantflora. Methods Fresh stools from patients and controls were inoculated on SS.,Mac Conkey and blood agar plates respectively and cultivated at 35 C for 24 ~ 48h, subsequent examinations of 1-3 species predominant colony from monocolony distributed over blood plates were made. Results Non-E. coli predominant flora were found in 73(67. 0% )patients with chronic diarrhea and none in controls (P<0. 001 ). The non--E. coli Predominant florain-cluded 22 species containing 76 strains bacteria and 3 strains fungii,of which G-bacilli were 17 species containing 55 strains, that mainly were Proteus mirabilis, Citrobacter freundii, Serratia liquetaciens, Klebsiella pneumoniae that possess 58. 0 % (32/55 ); G+ Cococci and Bacilli were 5 species containing 21 strains,mainly were Streptocococ-ci faecium and Baillus subtilis that possess 71. 4 % (15/21 ). Conclusion Chronic diarrhea correlates with the species of intestinal aerobic predominant flora. To our knowledge the correlation has not been reported.