Single strand conformational polymorphism (SSCP) is a recently developed technique used to detect single base mutations in short PCR-generated amplimers. The method has been adapted and applied to differentiation of beta-lactamase genes. Each of the five standard SHV strains used produced a unique SSCP pattern, allowing the possibility of rapid identification of the SHV genes of other isolates. A clinical isolate that phenotypically produced SHV-5 yielded a pattern of major bands indistinguishable from that of the SHV-5 standard strain, illustrating the applicability of this technique. We therefore report a reliable and reproducible technique that can be applied to the characterisation of the SHV beta-lactamases.