HTLV1 is a complex retrovirus belonging to the delta virus family (
4). HTLV1 infects 10 to 20 million people worldwide: Southern Japan, the Caribbean, Central and South Africa, South America, and the northeast of Iran are the endemic foci (
5). The prevalence of HTLV1 infections in Mashhad City (northeast of Iran) is 1.16% (
6,
7), and HTLV1 infects the body’s CD4 cells. There are several routes of viral transmission, including: sexual, mother to baby, transfusion, needle stick, and breast feeding (
8). The standard practice for a diagnosis of HTLV1 infection is the detection of antibodies by an enzyme immunoassay (EIA) technique, followed by a confirmatory test with Western blot or molecular methods (
9). HTLV1 has two major clinical presentations: 1) adult T-cell leukemia lymphoma (ATLL) and 2) a neurologic disease called HAM/TSP (
10). Patients with HAM/TSP present with spastic paraparesis in the lower extremities, mild disturbance of sensation and urinary dysfunction (
8). The pathogenesis of neurological manifestationsin a HTLV1 infection arepoorly understood. Up to 90% of HAM/TSP patients have urologic manifestations, such as: urgency, nocturia, urge incontinence, dysuria, and straining (
11,
12). In the aforementioned group, the major abnormality is over-active bladder syndrome, and detrusor over-activity, followed by detrusor external sphincter dyssynergia (
13). However, 3.84% of patients showed a hyporeflexic bladder and detrusor hypo-sensitivity and hypo-activity. In this group, the urological manifestation is bladder over-distention, secondary to a large volume of urine, which in turn causes hesitancy, sensation of incomplete voiding, and spontaneous bladder rupture (
14). A diagnosis of bladder rupture is difficult to make and it requires a high index of suspicion. The most common presentation is diffuse abdominal pain and lower abdominal tenderness, confirmation of the diagnosis is almost always done with a laparotomy (
5). In conclusion, bladder over-distention and spontaneous bladder rupture, although very rare in HAM/TSP patients, should be kept in mind when making a differential diagnosis of spontaneous bladder rupture, especially in a high HTLV1 prevalence country such as ours. In addition, aurodynamic evaluation should be performed in all HTLV1 infected individuals with voiding complaints.