Page kidney (PK) is the occurrence of kidney hypoperfusion and ischemia due to pressure on the kidney by a subcapsular hematoma (SH), a mass, or fluid collection. SH after renal transplantation may result in kidney ischemia and graft loss. We present a rare case of early spontaneous SH in an allograft kidney that led to a decrease in renal function. A 56-year-old male patient underwent deceased donor kidney transplantation. After declamping, appropriate renal perfusion and immediate diuresis were observed, with no evidence of SH. However, his urinary output abruptly decreased 6 h postoperatively. Abdominal ultrasonography showed 28 mm deep SH on transplant and the resistive index (RI) increased to 0.98-1 and diastolic flow reversal was observed. Surgical interventions were performed 2 days after transplantation, following a further decrease in urinary output. Serum creatinine decreased to 2.2 mg/dL, urinary output increased to an average of 200 cc per hour and the RI value was decreased to 0.7 on POD 7. In patients with abrupt decreased renal function after transplantation, SH should be suspected and the presence of PK should be determined using Doppler USG. In these cases, surgical intervention may avoid allograft dysfunction.