Background Few studies and small series have addressed the characteristics of pure membranous lupus nephritis (MLN). Objectives To establish the clinical characteristics, treatment and prognosis of MLN and to make international and intersocial comparisons. Methods Twenty-one Spanish centres and 1 in the US participated in the study. All SLE patients with biopsy proven MLN were included. Data on clinical and laboratory features, prescribed drugs, renal outcomes and survival were collected. Descriptive statistics were used to describe the main features of the series. Chi-squared distribution and Fisher test were use to analyse categorical variables and the U Mann-Whitney test for quantitative variable. A p value Results 134 patients were included (see table). Female sex (.036), a low basal serum creatinine (BSC) (0.92 Vs 1.53 mg/dl; Conclusions MLN usually begins with nephrotic syndrome, high proteinuria and normal BSC. Its prognosis is favourable in maintaining renal function although proteinuria usually persists over time. Cardiovascular disease and some socio-sanitary factors are related with bad prognosis. Disclosure of Interest None Declared