Background: The prevalence of asymptomatic renal scarring, such as a focal segmental glomerulosclerosis (FSGS), was suggested to be high in women who develop preeclampsia. FSGS is a risk factor for endstage renal disease. Objective: To document preeclamptic women with proteinuria that developed eight weeks prior to hypertension with confirmed FSGS postpartum. Case: A 20-year-old nulliparous Japanese woman with a negative dipstick test result at gestational week (GW) 18 exhibited proteinuria 1+ on dipstick test at GW 22. Proteinuria determined from the random urine protein to creatinine ratio (P/Cr, g/g) was increased from 3.7 at GW 26 to 4.6 and 8.9 at GW 28 and 30, respectively. She developed hypertension (142/66 mmHg) at GW 30. Due to increased edema, emergency cesarean section was performed at GW 33. She gave birth to an otherwise healthy female small-for-gestational-age infant, weighing 1290 g. Postpartum course was uneventful except for persisting proteinuria: P/Cr of 9.8 just before delivery decreased to 3.6 and 1.7 on postpartum weeks 9 and 17, respectively. Renal biopsy on postpartum week 13 revealed FSGS in this patient. Conclusion: Hidden FSGS may have manifested as preeclampsia in this patient. This case highlighted the need to determine the prevalence of asymptomatic FSGS among women who later develop preeclampsia.