By direct amplification and sequencing of genomic DNA by the polymerase chain reaction, we have identified a unique 2-base deletion in the growth hormone receptor gene of a patient with extreme short stature and growth hormone insensitivity (Laron) syndrome. We found a deletion of bases 118-119 in exon 4, which corresponds to the extracellular domain of the growth hormone receptor. Since this mutation encodes a frameshift in the amino acid sequence and a stop codon relatively early in the translation of the growth hormone receptor, we conclude that this deletion caused the growth hormone insensitivity in this patient.