We report a female newborn with type II mucolipidoses. This condition is characterized clinically by Hurler like features, progressive psychomotor retardation and death during the first or second year of life. Most cases present during the first year of life, with poor weight gain and coarse facies features. The cause of this rare autosomal recessive hereditary disease is the deficiency of the enzyme N-acetylglucosamine-1-phosphotransferase, required for the synthesis of mannose-6-phosphate, the ligand that allows the transport of acid hydrolases into lysosomes. The patient had clinical features commonly found in mucolipidosis II, including disproportionate dwarfism, retarded psychomotor development, coarse facies features, gibbous and restricted joint mobility. The diagnosis was proved by an extremely elevated activity of lysosomal enzymes in the serum, secondary to non-regulated secretion and subsequent intracellular depletion of these proteins. The child suffered recurrent pneumonia and died at 22 months of age (Rev Méd Chile 2003; 131: 314-9).