OBJECTIVE To report intravitreal triamcinolone (IVTA)-induced unmasking of ocular syphilis. METHODS Two case reports. METHODS A homosexual, diabetic male with macular edema treated with bilateral IVTA and a male with bilateral panuveitis and macular edema who underwent vitrectomy and IVTA. Both developed occlusive retinal vasculitis and panuveitis postinjection. Syphilis serology was positive although both denied previous symptoms. RESULTS Intramuscular penicillin lead to resolution of inflammation but both sustained severe loss of vision. Cause-and-effect relationship demonstrated between IVTA and reactivation of syphilis. CONCLUSIONS Intravitreal corticosteroid can modulate the immune response to intraocular syphilis; vigilance is required, particularly in high-risk patients.