PURPOSE We evaluated ejaculatory response and semen quality in 653 trials of penile vibratory stimulation in 211 men with spinal cord injury, and compared results with low versus high amplitude vibratory stimulation. MATERIALS AND METHODS Low and/or high amplitude penile vibratory stimulation was performed 1 to 27 times in each patient, and antegrade and retrograde specimens of those who ejaculated were analyzed. RESULTS Significantly more patients ejaculated using high (54.5%) versus low (39.9%) amplitude stimulation. Using either amplitude the ejaculatory success rate was highest in men with injuries at C3 to C7, followed by T1 to T5, T6 to T10 and T11 to L3. While high amplitude stimulation increased the ejaculatory success rate in each group, the highest rate occurred in men with injuries at C3 to C7 (65.6%). Ejaculation was reliable, since most men who ejaculated did so during 100% of the trials and within 2 minutes of stimulation onset. Symptoms of autonomic dysreflexia were safely managed with nifedipine. All patients who ejaculated produced antegrade specimens. With the exception of ejaculate volume, which was significantly higher with high versus low amplitude stimulation, semen parameters were similar using both vibrator amplitudes. CONCLUSIONS Ejaculatory success is better while semen quality is similar using high versus low amplitude penile vibratory stimulation in men with spinal cord injury. This method may be considered first line treatment for anejaculation in men with spinal cord injury due to its safety, relative effectiveness, and relatively low investment of time and money.