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Objective To define if antibodies to ribosomal P proteins disclose a better lupus nephritis long-term survival. Methods Sixty consecutive SLE patients with biopsy-proven nephritis (2004 ISN/RPS) were evaluated for renal survival parameters. Inclusion criteria were at least one serum sample at: renal flares, biopsy, and last follow-up until 2008. Anti-P was detected by ELISA/immunoblot and anti-dsDNA by indirect immunofluorescence/ELISA. Results Eleven patients (18%) with anti-P+ (without anti-dsDNA) during renal flare were compared to 49 (82%) persistently negative for anti-P throughout the study. At the final follow-up post-biopsy (6.3 ± 2.5 vs. 6.8 ± 2.4 years, p = 0.36), the comparison of anti-P+/anti-dsDNA− with anti-P− group revealed a trend to lower mean creatinine levels (0.9 ± 0.3 vs. 2.3 ± 2.1 mg/dl, p = 0.07), lower frequency of dialysis (0% vs. 35%, p = 0.025), and higher frequency of normal renal function (91% vs. 53%, p = 0.037). The overall renal survival was significantly higher in anti-P+/anti-dsDNA− compared to anti-P− (11.0 ± 4.5 vs. 9.2 ± 4.5 years, p = 0.033), anti-dsDNA+/anti-P− (vs. 8.7 ± 4.7 years, p = 0.017), and anti-P−/anti-dsDNA− (vs. 9.8 ± 4.3 years, p = 0.09) groups. Conclusion Our data supports the notion that anti-P antibody in the absence of anti-dsDNA during nephritis flares is a valuable marker to predict a better long-term renal outcome in lupus patients.