Older adults may be susceptible to injury during high-intensity resistance exercise. It has been suggested that it may be more protective to predict one-repetition maximum (1-RM) than to measure it because of the high intensity associated with 1-RM testing, but it may be necessary to measure 1-RM for functional, diagnostic, or clinical purposes. The method of using the OMNI Resistance Exercise Scale (OMNI-RES) was examined as a guide for hexagenarian adults in estimating 1-RM. 22 healthy men (M age = 64.3 yr., SD = 3.2) and 27 women (M age = 63.8 yr., SD = 2.8) volunteered. After two weeks of orientation, participants used a predetermined rating of perceived exertion to select resistance in the assessment of 1-RM and again after 12 weeks of training. At the 1-RM trials, participants were asked to report soreness or injury during or after the exercise sessions. There were no reported incidences of injury during the current investigation. The current results provide a practical method to estimate 1-RM in older adults. As such, the OMNI-RES can be used safely in a potentially at-risk population.