Mitochondrial DNA (mtDNA) from 100 unrelated British White Caucasians was extracted, amplified and directly sequenced. Sequences of approximately 800 nucleotides were obtained from 2 hypervariable segments within the non-coding region of the mitochondrial genome. A total of 91 different sequences were observed with an average nucleotide diversity of 1.1%. The most diverse pair of sequences differed at 3.6% of their nucleotide (nt) sites. Comparison to a consensus reference sequence showed that each region was polymorphic to a similar extent. Different methods of genetic analysis were used to examine the variation in each region, including pairwise comparisons, which demonstrated that although the data did not fit a Poisson distribution, the fit was closer to a Negative Binomial distribution.