Minimally invasive methods and devices for endoluminally treating female fallopian tubes or male vas deferens of mammals are presented as a permanent method of contraception. In preferred embodiments, medical devices for male and female sterilization comprise laser radiation source operating at one or more preselected wavelengths between about 980nm and about 1950nm, preferably at least one of 980nm, 1470nm and 1950nm; treatment waveguide with a radial or cylindrical radiation emitting tip; viewing scope; and a temperature sensor. In another preferred embodiment, a minimally-invasive permanent contraception method for males and females comprises the steps of introducing at least one treatment waveguide in a body cavity; positioning the treatment waveguide inside a body cavity; irradiating; and repeating the procedure in companion body cavity to inhibit fertilization. In another embodiment, fluids are infused and/or extracted after, before or during the procedure to enhance laser energy absorption and enhance efficiency of laser treatment.