The Lênaia, was held in January. It was dedicated to the god Dionysus Lênaios, and celebrated both his release from Zeus's thigh and his emergence from the Underworld.

According to myth, Dionysus was conceived in late February, and grew in the womb of his mother (Semele) for 7 months. Zeus struck her down, however, and then rescued the holy child Dionysus, whom he sewed into his thigh. According to mythology, these events took place during the grape harvest.

Whilst Dionysus was held in Zeus’ leg, the wine fermented in buried jugs. In January, when Dionysus emerged, the wine had cleared, and it was brought out of the Earth as well. Because January is also the time when, according to legend, Dionysus had also emerged from the Underworld, the Lenaia was a combined celebration of Dionysus’ ascension from the Underworld, his birth as the Divine Child and the arrival of a new vintage of wine.

The Festival consisted of a series of ritualised processions, holy rites and the performances of choric verses and plays.