The leaf anatomy of the Linaceae complex (Linaceae s.s., Hugoniaceae, Ixonanthaceae, Humiriaceae and Erythroxylaceae) and putative allies ( Ctenolophon, Lepidobotrys, Irvingiaceae) is surveyed, mostly on the basis of original observations (72 specimens, 27 genera), partly from data in the literature. Diversity in stomatal type, midrib and petiole vascularisation, sclerenchyma support, foliar sclereids, mucilage cells, secretory cavities, and cristarque cells provide evidence in favour of a separate family status of the members of the Linaceae complex. Allantospermum and Cyrillopsis are best accommodated in the Ixonanthaceae. Irvingiaceae (often treated in or near Simaroubaceae) show similarities with the Linaceae complex, albeit more closely to the Hugoniaceae than to the Ixonanthaceae to which they have been transferred by some authors. Ctenolophon seems unrelated, but leaf anatomy gives no strong clues for its true affinities. Lepidobotrys may be related to the Linaceae complex, but its leaf anatomy is also in good agreement with treatment in or near the Oxalidaceae. Within the Ixonanthaceae, Phyllocosmus deserves generic status next to Ochthocosmus on account of the exclusive occurrence of tracheoidal idioblasts in the latter and lack thereof in the former. The results are discussed in connection with evidence from other sources of enquiry.