A 7-year-old boy with acute lymphocytic leukemia developed iris infiltration, blood-streaked hypopyon, and high intraocular pressure. A diagnostic anterior chamber paracentesis was performed, which provided a cytologic diagnosis. The aspirate was studied by both the millipore filter technique with Papanicolaou stain and a dried smear using the Wright's stain. Wright's stain provided more distinct cellular details. Irradiation of the anterior segment resulted in clearing of leukemic iris infiltration, hypopyon, and glaucoma.