Purpose/Method A 15-year-old boy with bilateral blepharoptosis, bilateral type 1 Duane's retraction syndrome, and mild learning difficulties underwent chromosomal analysis. Results/Conclusions A de novo deletion of a segment of the long arm of chromosome 4 (4q27-31) was found. To our knowledge, no other individuals with this chromosome deletion have Duane's retraction syndrome. The chromosome defect lies close to the epidermal growth factor gene, 4q25, which was recently linked to Rieger's syndrome. We suggest that families with Duane's retraction syndrome should be assessed for linkage to the area of 4q27-31.