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Intravenous fluorescein angiography is a frequently used diagnostic imaging procedure used in ophthalmology for evaluation of the retina and other ocular structures. It is generally considered to be a safe procedure, but there have been reports of inaccurate laboratory test values in patients who have just undergone fluorescein angiography. Ophthalmologic literature has reported very little on this subject. It is important that both the ophthalmologist and the patient be aware of this possibility because patients who undergo angiographic testing often have other medical problems and may be scheduled for other tests. Using four volunteers this study examined the effects of intravenous injection of fluorescein angiography on blood and urine samples. These samples were analyzed by seven commonly used systems which produce panels of laboratory data results. The blood samples were drawn at intervals ranging from five minutes to 24 hours after fluorescein injection. Urine collection was begun immediately after injection. Analysis was performed by: Sequential Multiple Analyzer with Computer (SMAC), ASTRA and CX3, Automatic Clinical Analyzer (aca), electrophoresis, TDx, and COBAS. The serum protein electrophoresis was not affected by the fluorescein. The blood samples which were taken at five minutes and analyzed by SMAC, TDX and aca gave false results on the tests for serum creatinine, total protein, serum cortisol, digoxin, quinidine, thyroxine and amylase. After 12 hours all tests except cortisol, digoxin and thyroxine were unaffected; after 24 hours no interference was evident on any of the blood tests. Laboratory tests on 24-hour urine specimens were not affected by fluorescein. The authors advise that laboratory testing be conducted either before fluorescein angiography is performed or on the day following the imaging procedure.