Hi Rashmi, Don t get so tensed. There are several reasons for stool being black colour. It also depends on the food you eat or medicines you take. Stool can appear black if you eat a lot of blue berries or liquorice. Have you started taking Iron suppliments? Even this can cause black stools. If you have started taking iron suppliments, stop taking them for a week or so, to find out if this is the cause for black stools. Are you taking any medicines like aspirin, Ibuprofen, Warfarin etc? These medicines can sometimes cause intestinal bleeding resulting in black stools. If you are not taking any of the above and if you still have black stools even tomorrow, then it suggests bleeding in the upper gastrointestinal tract due to gastritis, gastric ulcer etc. You need to be investigated for it. I hope this helps.