The catalytic domain of SHP-1, a SH2-domain containing protein tyrosine phosphatase, has been crystallized by the vapor diffusion method using polyethylene glycol as the precipitant. The crystals belong to the monoclinic space group P2(1) with unit cell dimensions a = 42.12 Angstrom, b = 87.94 Angstrom, c = 43.22 Angstrom, alpha = 90.0 degrees, beta = 120.12 degrees, and gamma = 90.0 degrees. There is one catalytic domain of SHP-1 per asymmetric unit. X-ray was diffracted to at least 2.5 Angstrom and the crystals are appropriate for high-resolution structure determination. (C) 1997 Academic Press.