Two Japanese female adolescents with systemic lupus erythematosus (SLE), known cases of urinary tract involvements: one with biopsy-proven class II lupus nephritis and the other one with lupus cystitis without overt glomerulonephritis (silent lupus), who after more than 4 years’ observation presented with subsequent progression to membranous glomerulonephritis (MGN) following exacerbation of urticarial rash. Although it is well known that lupus nephritis shows histological transformation with time, the late progression to MGN from another World Health Organization histologic pattern has been reported to be less common in pediatric-onset SLE. Although pathogenesis of their MGN remains speculative, these clinical observation might suggest that a possible association between exacerbation of urticarial rash and subsequent progression to MGN in the selected patients with SLE.