We report here on the final results of an epidemiological survey involving 177 beta-thalassaemic chromosomes in Algeria. Four common mutations account for 86% of the chromosomes, the other ones carrying nine other rare mutations. Combination of these results with those of other smaller regional epidemiological studies indicates the existence of still a wider range of mutations. The nature and frequencies of these mutations, their linkage with RFLP-haplotypes, agree well with the history of the region. Knowledge of this spectrum of mutations enables the design of a diagnosis strategy that takes into account the local economical constraints.