Fluorescence microlymphography (FML) is an almost atraumatic technique used tovisualize the superficial skin network of initiallymphatics through the intact skin of man. Visualization was performed with an incidentlight fluorescence microscope followingsubepidermal injection of minute amounts ofFITC-dextran 150,000 using microneedles. Emanating from the bright dye depot, thesurrounding network of microvessels is filled, documentation performed by photography orvideo film. In congenital Milroy lymphedema, a lack of microlymphatics (aplasia) is typicalwhile in other primary lymphedemas and insecondary lymphedema after mastectomy orirradiation of proximal lymph nodes, thenetwork remains intact but the depicted areais enlarged. Lymphatic microangiopathycharacterized by obliterations of capillarymeshes or mesh segments develops in phleboedemawith trophic skin changes, progressivesystemic sclerosis and Fabry’s disease. Inlipedema, lymphatic microaneurysms arestained. Microlymphatic pressure may also bemeasured using FML. For this purpose, glassmicropipettes are inserted into the capillariesby means of a micromanipulator and pressureis determined by the servo-nulling technique. Normal subjects produced significantly lowerpressure (7.9±3.4 mmHg) compared topatients with primary lymphedema (15.0±5.1 mmHg, p< 0.001). This characteristiclymphatic hypertension may be improved bycomplex physiotherapy or local application ofprostaglandins. Additionally, a modificationof the FML procedure can be used to measurelymphatic capillary flow velocity in controlsand patients. FML is suited to confirm the clinicaldiagnosis of lymphedema, contributes todistinguish among various forms of edema, and is useful in clinical research. In addition, FML has also become a tool for experimentalanimal studies including the depiction ofgastric microlymphatics, the measurement offlow velocity in the naked mouse tail, and inevaluation of lymphangiogenesis in a modelof Milroy disease.