Since its introduction in 1989, analyses by SSCPA of DNA sequences containing mutations by SSCPA have increased dramatically. While many workers have recognised the utility of the technique, few have examined its limitations. In this paper we report studies using part of the lacI gene from E. coli to measure assay variables. When assay conditions are carefully controlled, the assay is very reproducible. The position and type of mutation have little effect on detection efficiency and changes in sequences 176 and 354 bp in length are detected with comparable efficiencies. Overall detection efficiency is > 90% under most conditions. However, local heating due to excessive power levels, can introduce anomalies.