Prostate enlargement is a common noncancerous condition. Urologists usually remove some prostate tissue by employing a procedure called transurethral resection, but some laser treatments may prove safer and more effective. Nathaniel M. Fried of the University of North Carolina at Charlotte has reviewed these treatments. Early laser treatments using a deeply penetrating 808-nm diode or a 1064-nm Nd:YAG laser caused a host of complications and proved less effective than transurethral resection. As a result, recent treatments have focused on the use of lasers with shallower penetration depths and more power, such as the KTP and the Ho:YAG. The 2120-nm Ho:YAG and 523-nm KTP lasers penetrate less deeply because their wavelengths are absorbed by water and blood, respectively. Short-term tests have shown that photoselective vaporization with the 80-W KTP laser is as effective as transurethral resection, and a new 120-W KTP laser promises to vaporize the prostate even more rapidly.Ho:YAG laser enucleation has established itself as a useful technique. Enucleation can treat extremely large prostates, it causes minimal bleeding, and it performs better than transurethral resection for treating small prostates. Although this technique requires expensive equipment, the cost may be offset because the method also can remove tumors, abnormal structures and stones. But, it is more difficult to learn than photoselective vaporization. With the introduction of more powerful 100-W lasers, it also may be worthwhile to re-explore Ho:YAG laser ablation and resection.Future developments in laser systems promise to improve treatment of prostate enlargement. New to urology, the CW thulium laser may cause less mechanical stress than the pulsed Ho:YAG. However, the similar wavelengths of the 2010-nm thulium laser and the 2120-nm Ho:YAG promise to allow the thullium laser to cut just as efficiently. The advent of the fiber laser has resulted in a tunable thulium laser that uses input power more efficiently than either the KTP or Ho:YAG lasers. In the future, urological laser systems will continue to become smaller and more efficient, the reviewer predicted. (Current Urology Reports, January 2007, pp. 47-52).