The eyes of 38 anesthetized rhesus monkeys were exposed to near-infrared laser radiation from a repetitive pulse gallium arsenide laser. Pulse repetition frequencies of 40 pps and 1,000 pps were utilized with a 20 nsec. pulse width at the wavelength of 905 nm. Lesions for threshold determination were placed in the temporal paramacular area and could be produced only by varying exposure duration with fixed energy output. Therefore, the resultant 50 probability of damage values ED-50 were expressed as total exposure duration rather than energy per pulse. The ED-50 value of 0.72 sec. for the 1, 000 pps exposure is significantly lower than the 22.3 sec. for the 40 pps exposure and demonstrates a cumulative effect.