A method for removing methylene-bridged polyphenyl polyamines from an aqueous stream comprising said methylene-bridged polyphenyl polyamines according to the invention comprises the steps of Providing a pertraction equipment comprising a membrane with a first side and a second side opposite to said first side; Bringing an aqueous stream comprising methylene-bridged polyphenyl polyamines into contact with the first side of the membrane and bringing an organic stream into contact with the second side of the membrane, thereby causing the methylene-bridged polyphenyl polyamines to transfer from the aqueous stream through the membrane to the organic stream. The method further comprises, before bringing the aqueous stream and organic stream in contact with the membrane, the step of wetting the membrane with a liquid having a surface tension of less than 40 mN/m.