Several studies have shown that the presence of genetic instability can be associated to carcinogenesis process. The detection of microsatellite instability (MI) that consists of an expansion and/or deletion of DNA within repeat sequences, may constitute a sensitive marker for the presence of gene mutations. A series of 18 basal cell carcinoma (BCC) consecutive patients was examined for the presence of alteration in 12 DNA microsatellite markers, in order to better understand the molecular significance of MI in the genesis and progression of BCC. Molecular alterations were detected in 6 out of 12 analyzed microsatellite loci. Five out of 18 BCC samples showed loss of heterozygosity at chromosome loci localized in the vicinity of the tumor suppressor genes, whereas six out of 18 BCC patients presented at least one altered microsatellite (instability). We demonstrated molecular genetic alterations at 2p16 locus, in the proximity of MSH2 <mismatch repair> gene and 17p21, in the proximity of the p53 gene. These data validate and confirm a role of MI in genesis and progression of BCC, by analysis of markers localized at specific chromosome region in proximity of oncogenes and tumor suppressor genes.