Abstract: The invention relates to a chemical treatment system for manufacture of paper, board or the like and to a method employing it. The system comprises a first component, which is a glyoxylated polyacrylamide having a net cationic charge density and obtained by glyoxylation of a cationic polyacrylamide base polymer having a weight average molecular weight MW in a range of 30 000-500 000 g/mol. The system further comprises a second component, which comprises a mixture of at least a high-amylopectin starch, and an anionic first polymer, which has a weight average molecular weight MW>200 000 g/mol. The second component has a net cationic charge density in a range from 0.05 meq/g to 0.9 meq/g, when measured at pH 2.8, and a net anionic charge density in a range from ?2 meq/g to ?0.1 meq/g, when measured at pH 7.