In a method and an apparatus furfural is recovered from a steam stream (3) which is formed in a treatment of a pretreated wood based material (1). The pretreated wood based material (1) which comprises at least carbohydrates is treated in a steam treatment stage (2) in which the steam is released. The steam stream (3) which comprises furfural is supplied out from the steam treatment stage (2). A pretreated and steam-treated wood based material (4) which comprises carbohydrates is supplied out from the steam treatment stage (2), and the steam stream (3) is treated in a recovery stage (12a, 12b) for recovering a furfural based fraction (14a,14b).