Hurler Syndrome is Type I MPS due to deficient enzyme activity of alpha-L-Iduronidase. Dermatan sulphate and Heparan sulphate are excreted in urine. It is an autosomal recessive disorder. Patients present with cognitive degeneration, hepatosplenomegaly, skeletal dysplasia, corneal clouding, coarse facies & cardiovascular involvement. Clinical onset is infantile or intermediate. An important hematologic finding is vacuolated lymphocytes.