By means of PCR and using synthetic oligonucleotides designed from the reported cDNA, we amplified the gene that codes for toxin IV-5 from the Brazilian scorpion Tityus serrulatus. The analysis of the nucleotide sequence shows that the amplified genomic region is composed of 659 base pairs (bp) comprising two exons (28 and 284 bp) and an intron of 347 bp interrupting the region that encodes the signal peptide of the precursor toxin. Based on these findings a model for the structural organization of scorpion toxin genes is proposed.