Biostatistical Parameters such as the paternal markers in the child (PM), individual exclusion change (IEC) probability of incidental involvement (Z), probability of paternity (POP), plausibility of paternity according to Essen-M oller ( PLEM ) and paternity index (PI) are defined and discussed in respect to their application in cases of disputed paternity. In order to calculate these parameters for up to 24 marker systems, including HLA under strict observation of the linkage disequilibrium, a computer programme in BASIC has been developed.