X-chromosomal markers in forensic genetics have become more widely used during recent years, particularly for relationship testing. Linkage and linkage disequilibrium (LD) must typically be accounted for when using close X-chromosomal markers. Thus, when producing the weight-of-evidence, given by a DNA-analysis with markers that are linked, the normally used product rule is invalid. Using a simulation approach the current study showed that the use of X-chromosome data can offer valuable information for choosing between the alternatives in each of the cases studied, and that the LR can be high in several cases. The study demonstrated that when linkage and LD were disregarded, as opposed to taken into account, the difference in calculated LRs could be considerable. When these differences were large, the estimated haplotype frequencies often had a strong impact and the authors present a method to estimate haplotype frequencies. The authors' conclusion is that linkage and LD should be accounted for when using the tested set of markers, and the used model is an efficient way of doing so. (Published Abstract)