The Salmonella genomic island 1 is an integrative mobilizable element (IME) originally identified in epidemic multidrug-resistant Salmonella enterica Typhimurium DT104. The occurrence of SGI1 in several S. enterica serovars and recently in Proteus mirabilis has led to demonstrate its horizontal transfer. SGI1 excises from the donor chromosome to form a circular extrachromosomal intermediate that can be mobilized in trans to the recipient. SGI1 integrates site-specifically into the chromosome at the 3’ end of the trmE gene. Here, we have studied the mechanism of conjugative transfer of SGI1. First, we have shown by SGI1 mobilization assays with different plasmid incompatibility groups that only multidrug-resistance IncA/C plasmids were able to mobilize SGI1. The transfer origin of SGI1 has been located on a 135 bp DNA region by mobilization assays of a non mobile plasmid containing this region. The decrease in transfer frequency of a SGI1 lacking this putative oriT region confirmed this location. The involvement in the SGI1 transfer of the S020 ORF coding for a putative integrase was also demonstrated. One other region located between S013-S019 ORFs contained an element required for SGI1 mobilization. The identification of the different molecular components involved in SGI1 mobilization is an important step for understanding the dissemination of the genomic island.