Abstract Basic ideas and recent developments in network analysis of metabolic systems and various applications of this analysis in bioengineering are reviewed. Central con-cepts are the null-space to the stoichiometry matrix and the elementary flux modes. The applicability of elemen-tary-modes analysis in biotechnology is illustrated by the synthesis of the cyclooctadepsipeptides PF1022 in the fungus Mycelia sterilia. Network analysis is also useful in metabolic flux analysis. In particular, a procedure for finding out which reaction rates can be uniquely calculated in underdetermined reaction networks is outlined. The concept of ‘enzyme subsets ’ is explained and its use for analysing genetic regulation is demonstrated. In particu-lar, the...