['To assess the diagnostic yield of vitreous fluid analysis and the therapeutic effect of pars plana vitrectomy in patients with suspected intraocular inflammation.', 'During 2004-2008, pars plana vitrectomy was performed in 89 patients (101 eyes) out of 1233 patients with uveitis. Vitreous specimens were analyzed by cytologic and histopathologic examination, microbiologic culture, polymerase chain reaction, antibody determination, and flow cytometry. Vitrectomy was performed in 85 eyes for both diagnostic and therapeutic purposes; the remaining 16 eyes underwent only diagnostic pars plana vitrectomy. Preoperative and postoperative best-corrected Snellen visual acuity was compared.', 'Preoperative diagnoses were infection in 40 patients, malignant masquerade syndrome in 10 patients, and idiopathic uveitis in 39 patients. Vitreous analysis contributed to the determination of diagnosis in 54 patients (61%). Final diagnoses were infection in 42 patients, malignant masquerade syndrome in 6 patients, benign masquerade syndrome in 16 patients, and idiopathic uveitis in 25 patients. Vitreous fluid collected from each eye underwent approximately 2.2 (range 1-6) laboratory tests. Therapeutic reasons for vitrectomy were the treatment of complications of uveitis in 42 eyes and/or intravitreal application of anti-infectious or cytostatic drugs in 49 eyes. Overall, the visual acuity improved in 45% of eyes, remained unchanged in 45% of eyes, and decreased in 10% of eyes in 3 months after surgery.'] Do the role of pars plana vitrectomy in the diagnosis and treatment of uveitis?