Renal disease is common in sickle cell anemia. In this exploratory work, we used data from a longitudinal study of the natural history of sickle cell disease to examine the hypothesis that polymorphisms (SNPs) in selected candidate genes are associated with glomerular filtration rate (GFR). DNA samples and clinical and laboratory data were available for 1,140 patients with sickle cell anemia. GFR was estimated using the Cockcroft-Gault and Schwartz formulas for adults and children, respectively. We examined ∽175 haplotype tagging (ht) SNPs in about 70 genes of the TGFβ/BMP pathway for their association with GFR using linear regression. Four SNPs inBMPR1B, a bone morphogenetic protein (BMP) receptor gene, yielded statistically signi ficant associations (Pvalues ranging from 0.015 to 0.046). Three haplotypes in this gene were also associated with GFR. The TGF-β/BMP pathway has been associated with the development of diabetic nephropathy, which has some features in common with sickle cell nephropathy. Our results suggest that, as with other subphenotypes of sickle cell disease, renal function may be genetically modulated.