BACKGROUNDAnterior lumbar fusion procedures have many benefits and continue to grow in popularity. The technique has many potential approach- and procedure-related complications. Symptomatic retroperitoneal fluid collections are uncommon but potentially serious complications after anterior lumbar procedures. Collection types include hematomas, urinomas, chyloperitoneum, cerebrospinal fluid collections, and deep infections.OBSERVATIONSThe authors present an unusual case of a patient with persistent symptoms related to a retroperitoneal collection over a 5-year period following anterior lumbar fusion surgery. To the authors’ knowledge, no similar case with such extensive symptom duration has been described. The patient had an infected encapsulated fluid collection. The collection was presumed to be a postoperative lymphocele that was secondarily infected after serial percutaneous drainage procedures.LESSONSWhen retroperitoneal collections occur after anterior retroperitoneal approaches, clinical clues, such as timing of symptoms, hypotension, acute anemia, urinary tract infection, hydronephrosis, elevated serum creatinine and blood urea nitrogen, low-pressure headaches, anorexia, or systemic signs of infection, can help narrow the differential. Retroperitoneal collections may continue to be symptomatic many years after anterior lumbar surgery. The collections may become infected after serial percutaneous drainage or prolonged continuous drainage. Encapsulated, infected fluid collections typically require surgical debridement of the capsule and its contents.