Buddhist Lent (Thai พรรษา, pansa or phansaa) is a three month period during the rainy season in Thailand during which Buddhist monks remain in their temples. It is also known as the Rains Retreat.

The origins of the Buddhist Lent tradition are ascribed to early Buddhist times. The Buddha ordered his disciples to observe a pre-existing practice whereby holy men avoided travelling for a three month period during the rainy season, in order to avoid damaging crops.

The period begins on the first day of the waning moon in the eighth lunar month: the preceding day is Asanha Puja. The focus of celebration by the laity is the first day of lent, Wan Kao Pansa; worshippers donate candles and other necessities to temples, a ceremony which has reached its most extravagant form in the Ubon Ratchathani Candle Festival. Some also follow practices similar to those of Christian Lent throughout the period, such as following the five precepts. It is common for men to become monks temporarily during this period, albeit sometimes only for a few days.

Buddhist Lent lasts three lunar months; its end is marked by Wan Awk Pansa.