Gertrude van der Oosten (Gertrude of Delft) was born in Voorburcht, Netherlands, whose location is unclear, and died at Delft, 6 January 1358. She was a Dutch Beguine and was considered a mystic.
She was born of peasant parents, and entered into domestic service at Delft. Her surname of "van Ooten", or "of the East", is due to her custom of singing a hymn which began: "Het daghet in den Oosten", i.e., "Daylight breaks in the East", the composition of which is attributed to her herself.
She obtained admission into the Beguinage of Delft. Here, though not a nun, nor bound by vows, she profited by the ample opportunities for contemplation afforded by life in this community. Gertrude evidenced great devotion to the mysteries of the Incarnation, especially to the Sacred Passion of Christ, on which account she received on her body the impression of the sacred Stigmata. She begged that the favour might be withdrawn, and her prayer was so far granted that the blood ceased to flow, but the marks of the Stigmata remained. At the same time she had was favoured with the gift of prophecy.
She died on the feast day of the Epiphany and was buried in the church of St. Hippolytus in Delft. Her name has never been inscribed in the Roman Martyrology, though she is commemorated in various others, and her [[cult (religious practice)#Roman Catholic cultus|cultus]] is merely a local one.