Urinary dysfunction is a common complaint following spinal cord injury (SCI), and is a leading issue for individuals with SCI that impacts their quality of life. One urinary complication that has received little attention is SCI-induced polyuria, even though SCI individuals will significantly restrict their fluid intake to decrease urine production leading to a sequelae of medical complications. Understanding the mechanisms instigating the development of polyuria will allow us to target interventions which may alleviate polyuria symptoms leading to significant improvements in the quality of life and urinary health of SCI individuals. In a rat SCI contusion model, an increase in the amount of urine excreted over a 24 hour period (p ≤ 0.001) was found at two weeks post-injury. The urine excreted was more dilute with decreased urinary creatinine and specific gravity (p ≤ 0.001). Several factors important in fluid balance regulation - vasopressin (AVP), natriuretic peptides, and corticosterone (CORT) also changed significantly post-injury. AVP levels decreased (p = 0.042) while atrial natriuretic peptide (ANP) and CORT increased (p = 0.005; p = 0.031, respectively) at two weeks post-injury. There was also a positive correlation between the increase in ANP and urine volume post-injury (p = 0.033). The changes in AVP, ANP and CORT are conducive to producing polyuria, and the timing of these changes coincides with the development of SCI-induced polyuria. This study identifies several therapeutic targets that could be used to ameliorate polyuria symptoms and improve quality of life in SCI individuals.