The memorial monument on the grounds of the museum is the center of an annual remembrance day of the spirits of victims. Food and other offerings are made to the monks and as charitable acts to the poor. The event takes place each year on 20 May. Museum visitors are welcome to make charitable donations in observance of this day.
The largest annual ceremony for the museum, attended by governmental officials over two days, Pchum Ben, concludes a two-week period of offerings and prayers to the ancestral spirits. The event is unique to Cambodia, and the museum adds a monk each year to mark the passage of time from 1979, when the Khmer Rouge fell. Generally, Pchum Ben will take place accordingly to the lunar calendar.
January 7 marks the end of the Khmer Rouge regime in 1979, the brutal regime where millions of inno-cent people died. This date is celebrated annually in Cambodia to commemorate the Kampuchea United Front for National Salvation, who liberated together with the Vietnamese army, the Cambodian People from the regime.
Each year, Tuol Sleng Genocide Museum marks the Khmer New Year with a special ceremony to bless the staff and to bring offerings to victims through a religious ritual performed by Buddhist monks. Visitors are invited to join. The event is held annually on 8 April.