Amelogenesis imperfecta (Al) is a heterogeneous genetic disorder that affects the formation of the dental enamel matrix. Mutations in the enamelin (ENAM) gene have been found in patients with this disorder. The objective of this research was to identify the mutations reported in exons 4, 7 and 9 of the ENAM gene in a single Colombian family with autosomal-dominant Al and to establish the phenotype. The fragments of exons 4,7 and 9 of the ENAM gene were amplified by polymerase chain reaction and direct sequencing was performed. A mutation was found in exon 9 where guanine was substituted by thymine in one of the alleles in position 817, generating a change of arginine to methionine in codon 179 of the protein. The mutation was only found in affected members of this family who presented with the severe, generalised hypoplastic phenotype in all teeth. The genotype/phenotype correlation for different Al subtypes has not been established. These results support a possible correlation between hypoplastic Al and mutations in the ENAM gene; however, identification of additional mutations could be helpful in establishing phenotype/genotype relationships.