We studied 118 patients; 63 patients had ED secondary to radical prostatectomy (PED) and 55 had organic, clinical ED. eNOS genotypes for three eNOS polymorphisms (T(-786)C, rs2070744; a variable number of tandem repeats (VNTR) in intron 4; and Glu298Asp, rs1799983) were determined, and eNOS haplotypes were estimated using PHASE 2.1.