We studied a heterozygous beta zero-thalassaemia patient from Croatia with an unusually high Hb A2 level of 7.6% and an elevated Hb F level of 5.8%. The same condition was found in his father (Hb A2 8.2%; Hb F 8.5%). Gene mapping and direct sequencing analyses revealed a new deletion of 1605 bp in the 5' beta-globin gene region between positions -984/5 and +620/1. This deletion has not been observed among more than 500 beta-thalassaemia chromosomes from the Balkan countries studied in our laboratory.