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5-Fluorouracil (5-FU) is a commonly used chemotherapeutic agent used alone or in combination to treat a variety of cancers particularly of gastrointestinal origin. Skin hyper pigmentation is a very rare adverse event occurring with 5-FU infusions occurring in 2 to 5% of cases. This has become even rare due to versatile use of peripherally inserted central catheters and chemo ports in patients requiring prolonged infusions. We are hereby reporting this rare tree bark like Serpigenous supravenous skin pigmentation in a patient receiving prolonged 5-flourouracil infusion who denied for chemo port insertion. It resolved spontaneously over a month in left upper limb veins, but appeared again in right side when these veins are used in next cycle of chemotherapy. No alteration in drug dose or discontinuation of chemotherapy is needed in this condition as underlying veins are patent unlike in thrombophlebitis.