Testicular cancer (TC) is the most common cancer in 15-34-year-old males, but many young men are unaware of their risks, symptoms, and possibility of detection by testicular self-examination (TSE). After a pretest to determine baseline knowledge and TSE activity, 66 young men, 15-20 years old ( x ̄ = 18.5 ± 1.5), were given a programmed-learning self-instructional booklet to read. A posttest after completion of reading the booklet assessed attitudes and new knowledge. A 2-year follow-up tested knowledge and current TSE activity. Pretest analysis revealed that only 15% of the subjects were aware of their risks of TC, and only 6% had been taught TSE by a health professional. Subjects were unable to correctly identify the symptoms of TC, and only 1.5% reported regularly performing TSE. At 2-year follow-up, 95% (p < .001) knew that a small lump was the most common symptom of TC, and 67% reported performance of TSE (p < .001). These results suggest that adolescent males are not being taught about TC and TSE, and that our booklet is effective in teaching young men about TC risks and symptoms and how to perform TSE. This self-instruction method may be useful in health education classes for high school and college age youth. © 1990.