Objectives: To determine whether saturation needle biopsy of the prostate (SBx) can accurately predict prostate cancer (PCA) location in radical prostatectomy (RP) specimens. The success of focal therapy for PCA relies on accurate mapping of cancer before the procedure. Methods: A total of 72 patients underwent SBx followed by RP for PCA. The biopsy protocol consisted of traditional sextant, plus additional <10 cores. A single pathologist mapped the tumor outline on RP, determined the number of PCA foci, their Gleason score (GS), and stage. Results: Patients' median age and preoperative serum prostate-specific antigen was 60 years and 5.6 ng/mL, respectively. SBx detected bilateral PCA in 33 and unilateral PCA in 39 men. All cases with bilateral PCA by SBx had bilateral tumor in RP. Only 4 of 39 patients with unilateral positive SBx had unilateral cancer in RP. Twelve potentially clinically significant PCA were missed by SBx in 11 of 35 patients: 2 were GS6 and 10 GS7; 11 were stage pT2 and 1 pT3. When patients with unilateral and bilateral positive SBx were compared with respect to prognostic parameters, biopsy GS (P = .004), number of biopsy cores involved (P <.0001), and highest percentage of core (P = .0005) involved by tumor were significantly higher for patients with bilateral positive biopsy. Conclusions: Most (90%) patients with unilateral PCA on SBx had bilateral cancer in RP; of those 31% had clinically significant undiagnosed PCA. A negative SBx does not confirm the absence of cancer in the corresponding side of the gland and cannot be used as single determinant when considering a patient for focal treatment. © 2010 Elsevier Inc.