We reviewed the records of 32 consecutive children (43 eyes) who underwent lensectomy/vitrectomy between January 1988 and August 1990 at the Medical Center of the University of California at San Francisco, to study the incidence and characteristics of clinically significant postoperative inflammation (CSPI). No eyes of patients 18 months old or younger (22 eyes) developed CSPI; nine of 21 eyes of older patients did develop CSPI. Other ocular abnormalities (microphthalmos, persistent hyperplastic primary vitreous, retinopathy of prematurity, and Axenfeld's syndrome) and systemic syndromes did not influence the incidence of CSPI. Prolonged inflammation delayed refractive and amblyopia therapy but did not affect final visual acuity. The absence of CSPI in younger patients may be related to the general immaturity of their immune system and a resultant weak inflammatory response, or to their specific immunologic tolerance to lens crystallins.