Our objective was to investigate IgG glycosylation and disease activity post partum in the MRL-lpr/lpr mouse. Disease activity was monitored using bimalleolar ankle swelling. Levels of galactose and N-acetylglucosamine (GlcNAc) on IgG isolated from serum were measured using biotinylated lectins. Our results show that disease severity increased post partum. This post-partum flare correlated significantly with an increase in IgG GlcNAc expression. The disease severity increased post partum in the MRL-lpr/lpr mouse model similar to the changes seen in rheumatoid arthritis (RA).