Bhisma-pancaka refers to a special vow (vrata) that can be taken up by Vaisnavas during the last five days of the Damodara month. The vow is to eat only fruits and roots, abstaining from any type of grain. Some devotees during Bhisma-pancaka consume only panca-gavya or the five cow products — cow dung, cow urine, cow milk, ghee and yogurt.

Due to many circumstances, it may not be possible to fast during all the four months of caturmasya, so by following Bhisma-pancaka, one receives the benefit of fasting throughout the whole caturmasya.

Some devotees gather at Mayapur to observe this vow in the holy dhama in the association of the devotees. They take bath in the holy Ganga and offer oblations to Bhismadeva on all the days of the vow.