In this review the evidence from human clinical scenarios and the impact of probiotics to modulate the human gut microecology to prevention and management of diarrhea disease. Probiotics not only help digestive tract function, they also reduce the presence of less healthful organisms by competing with them for the limited available space. For this reason, use of probiotics can help prevent infectious diarrhea. Antibiotics can breakdown the balance of microbial ecology of the gut by killing and eradicate beneficial bacteria. When this happens, opportunistic bacteria and harmful yeasts can move in and flourish.. The development of probiotic, aims to “coin with two faces or Two Sides of a Coin”, which is accomplished by providing a microbial stimulus to the host immune system by means of beneficial live microorganism cultures that are characteristic of the healthy, human gut microbiota, ie, probiotics and reinforce the different lines of gut defense, which are immune exclusion, immune elimination and immune regulation. They were also shown to stimulate nonspecific host resistance to microbial pathogens, thereby aiding in pathogen eradication. Consequently, the best documented clinical trials of probiotics is in the treatment of diarrhea. Other health effects of probiotic bacteria have not been well established. Welldesigned placebo-controlled studies with validated outcome variables are needed to determine the health effects of probiotics.