The invention provides a process for the preparation of polyamines of the diphenylmethane series. This process comprises a) reacting aniline and formaldehyde in a molar ratio of 1.5:1 to 6:1, in the presence of an acid catalyst at temperatures of 20.degree. C. to 100.degree. C., in which the water content in the acid reaction mixture is <20 wt. % and a degree of protonation of <15% is established, and b) increasing the temperature of the reaction to a temperature of 110.degree. C. to 250.degree. C. when the ratio of the weight contents of p-aminobenzylaniline to 4,4'-MDA in the reaction mixture falls below a value of 1.00.