Opsoclonus is a rare childhood ocular motility disorder characterized by irregular, chaotic, involuntary bursts of high amplitude, back-and-forth oscillations of the eyes,without pause intervals. Although this disorder is associated with neuroblastoma and other neural crest tumors, as well as with other neurologic abnormalities, it was also reported in healthy infants. The purpose of this study was to prospectively investigate the prevalence of opsoclonus in preterm infants, and to find any conditions associated with this disorder. Between August 2000 and April 2003, 528 consecutive preterm infants with gestation of less than 33 weeks or birth weight of less than 1500 gm were examined in accordance with our medical centers' retinopathy of prematurity screening policy. Opsoclonus was identified in three patients (0.6%), who were all otherwise physically and neurologically intact. One patient developed threshold retinopathy of prematurity that resolved after laser treatment. On follow-up examinations, the opsoclonus gradually disappeared by the age of 6 months in all infants,with no other complications. This study suggests that opsoclonus can be a benign, self-limiting phenomenon in preterm infants as was previously reported in term infants. However, because of the risk of severe associated illnesses, it is prudent to perform several diagnostic procedures and to continue careful follow-up until this phenomenon spontaneously resolves.