Abstract:This work was aimed to study the effect of some probiotic microorganisms on fungi causing diarrhea. Therefore a total of (45) stool sample were collected from children(2 - 10)years old with diarrhea. Results observed that 15(33.3%) isolates belong to genus Candida, and 4(8.8%) of isolates belong to Candida albicans according to the related biochemical tests. Another part of the study included isolation of Lactobacillus (LAB) isolates for using as probiotics to test there ability to inhibit growth and forming germ tube by Candida albicans. Seven isolates of LAB were obtained from (45) stool samples after culturing on (MRS) medium for 24 hr at 37C0. The minimum inhibition concentration of nystatin to the isolates of Candida albicans was 200 ?g/ml liquid media and (16*104), While for the original sample (133*10 4) when cultured on SDA media. Upon such results, one isolate (C.2) of Candida albicans was chosen due to its ability to form high number of germ tube compared with other isolates, and secondly, three isolates of LAB: Lactobacillus acidophilus (Lb.1), Lactobacillus plantarum (Lb.5) and Lactobacillus fermentum (Lb.7) due to high number of colonies they formed when grown on MRS agar. No inhibitory activity was detected through the antagonism with Candida albicans when the novel methods "Candida albicans germ tube assay" was used. Minimum inhibition concentration was determined for the three - fold concentrated filtrate of LAB against germ tube formation by Candida albicans (C.2) isolate. Results showed that filtrates were able to decrease the extension of germ tube when compared with control. The average decreases were (1 - 5)%, (7 - 10)% and (20 - 30)% instead of 70% for the control growth.