Cephalosporin C acylase from Pseudomonas sp. strain N176, a heterodimer of 25 and 58 kDa, has been crystallized using polyethylene glycol 6000 as precipitant. The crystals are orthorhombic and have unit-cell parameters a = 141.41, b = 192.10, c = 80.75 A. They belong to space group P2(1)2(1)2(1) and diffract to at least 2.7 A resolution. Calculations indicate that there are two heterodimers in the asymmetric unit. The structure is being solved by molecular replacement using penicillin G acylase from Escherichia coli as a search model and by multiple isomorphous replacement.