In this study, the GenomiPhi(TM) DNA Amplification Kit (Amersham Biosciences) was used to investigate the potential of whole genome amplification (WGA) when considering samples originating from more than one donor. DNA was extracted from blood samples, quantified and normalised before being mixed in ratios of 1:1, 1:3, 1:7 and 1:15. Proportions were checked using standard STR analysis before being subjected to WGA. Once amplified using GenomiPhi(TM), the ratios were again checked. Relative proportions were found to be maintained in the 1:1 and 1:3 ratios following WGA; the observed peak ratios were found to match the expected peak ratios regardless of the starting concentration of DNA. With samples mixed in the ratio of 1:7 and 1:15, and when the concentration of starting material was at the manufacturer's lower limit, too few minor component peaks were found to allow for statistical analysis. With an initial template exceeding 1 ng/[mu]L there was an increase in problems associated with profile interpretation but the results obtained indicated that mixture proportions could be quantifiably maintained