GAP 31 is an anti-HIV plant protein that we have identified and purified to homogeneity from Gelonium multiflorum. It is the first reported example of an anti-HIV agent capable of acting against multiple stages of the viral life cycle, on viral infection and viral replication. GAP 31 is a unique paragon of multi-functional protein. In addition to anti-HIV activity, it also exhibits anti-tumor action, DNA binding, RNA binding and ribosome inactivation. The present crystals diffract up to 2.0 A resolution and belong to monoclinic space group P2(1). The cell dimensions are a = 49.30(2) A, b = 44.57(2) A, c = 137.78(7) A and beta = 98.32(3) degrees. There are two molecules of molecular weight 31 kDa in an asymmetric unit with a solvent content of 49%.