Mahadwadasi is an important day associated with Vaishnavas and those observing Ekadasi Fasting. If majority of the Ekadasi fasting is observed on the Dwadasi day (12 th day) instead of the 11 th day then this Dwadasi is referred to as Mahadwadasi. Such Ekadasi fasting is observed on the Dwadasi and is broken on the 13 th day day (trayodasi tithi). Mahadwadasi happens a couple of times in a Hindu lunar calendar. There is no other specialty attached to the day.