L-Asparaginase is an enzyme which hydrolyzes asparagine to produce aspartic acid and ammonia. It is an effective chemotherapeutic drug, especially in the treatment of acute lymphoblastic leukaemia in children. The enzyme from Escherichia coli was crystallized in a new crystal form with space group C2, unit-cell parameters a = 76.3 (0), b = 134.6 (2), c = 64.8 (7) A, beta = 110.5 (1) degrees and a dimer in the asymmetric unit. Synchrotron-radiation diffraction data have been collected to 1.95 A resolution.