Deletion pattern analysis of the dystrophin gene was performed in 115 unrelated Czech patients with Duchenne and Becker muscular dystrophy. In 50 patients (43.5% of the analysed patients) exon deletions were detected by routinely performed multiplex PCR for 18 selected exons and for the area of musclespecific promoter of the dystrophin gene. All startpoints and endpoints of deletions (100 breakpoints) were detected using PCRs for another 29 exon areas of the dystrophin gene (altogether primers for 47 different exons were used). Most of the breakpoints were found in introns 44 (16% of breakpoints), 47 (14%) and 50 (8%). The comparison of distributions of breakpoints in the area of the main hot spot of the dystrophin gene (introns 43-52) was made (chi 2 test in a contingency table) in six different populations from the Czech Republic, Bulgaria, Hungary, Italy, Turkey and India. In compared populations, statistically significant differences were found by the pooled test. No significant difference between the Czech population and other studied populations was found by pair comparisons. On the other hand, pair comparisons revealed significant differences between populations from Bulgaria and Hungary, Bulgaria and Turkey, Hungary and Italy. The results of the presented study support the theory suggested by other authors that specific differences in intron sequences of the dystrophin gene can exist between different populations, possibly as a result of a genetic drift.