Introduction: Autoantibodies to U1-RNP, Sm and Ro/SSA have been reported with increased frequencies in AA patients with Lupus, particularly in the southern region of the country. Crescents, a particularly ominous sign in Lupus Nephritis (LN), were present in one third of the biopsy specimens from AA patients with severe clinical LN followed in our clinic. Aim: To look for associations between the presence of crescents and the aforementioned autoantibodies. Methods: Biopsy specimens (18) from 15 consecutive AA patients (13 females) with severe clinical LN were evaluated by an integrated method of High Resolution Microscopy (plastic histotechnology), Transmission Electron Microscopy, and Direct Immunofluorescence. An independent pathologist without knowledge of patients' clinical and serological status registered data. Then two groups were conformed according to the presence or not of Crescents. Anti double stranded DNA (dsDNA) antibodies and antibodies to Sm, U1-RNP, Ro/SSA and La/SSB were determined by double diffusion. Results: Group with crescents (n=7) did not differed from group without crescents (n=8) in sex ratio (6:1 vs 7:1), age at diagnosis (26.1±8.6 vs. 27±12.1years), and disease duration (7.4±7.7 vs. 7±7.7 years). However, group with crescents had higher serum creatinine level (2.04 ±1.3 vs 0.98± 0.36 mg/dl) and clustered in WHO LN classes III (1 patient), IV (3 patients), and Vd (3 patients). All patients without crescents were in Class Va or Vb. Correlation with autoantibodies are shown in table: RNP Sm Ro/SSA La/SSB dsDNA RNP+(Sm and/or SSA) CRESCENTS n=7 7 5 5 3 5 6* NO CRESCENTS n=8 5 1 2 0 5 2* * p value <0.0026 (Z test) Conclusion: Crescents associate with more severe WHO LN classes and with antibodies to RNP plus Sm and /or Ro/SSA. Further studies are required in larger number of patients to fully assess the significance and potential prognostic value of this association.