90 patients scheduled for anterior cruciate ligament reconstruction with a hamstring autograft were randomized to either have the ends of the graft treated with calcium chloride and sodium phosphate solutions for calcium phosphate hybridization (CaP group), or to no treatment of the graft. Patients were assessed on CT scans for increase in cross-sectional area of the femoral and tibial bone tunnels to measure bone tunnel enlargement, as well as for the incidence of rerupture, objective and subjective knee laxity measures, and knee function scores. Follow-up was performed at 1 and 2 years postoperatively. The only significant difference observed between groups was in the increase in cross-sectional area of the femoral tunnel after 1 year, which was lower in the CaP group; the difference between groups at 2 years was not significant. In addition, no significant differences between groups were observed in tibial tunnel enlargement, rerupture rate, KT-1000 arthrometer results, pivot-shift test result, International Knee Documentation Committee grading, Lysholm score, or Tegner activity scale grading.