Lifting and transferring patients have been identified as frequent precipitating factors or causes of low back problems among nurses. This study systematically evaluated six different transfer methods (three manual and three mechanical) completed by two female nurses working as a team to transfer two totally dependent patients (heavy, 95 kg and light, 56 kg). The patient transfers were completed on a rehabilitation unit of a large university hospital. Each transfer was videotaped and the short (150 cm) and tall (178 cm) nurse each performed the lead and assist roles using all six methods for both patients for a total of 24 transfers. A biomechanical software program referred to as the "3-Dimensional Static Strength Prediction Program (3DSSPPTM)" was used to model each patient transfer, and to compute the peak compressive force on the L5/S1 disc, as well as estimate the percent of the population with sufficient strength capability to transfer patients. The results of biomechanical analysis revealed that the low back compression forces exceeded the back compression design limit recommended by the National Institute for Occupational Safety and Health (NIOSH) (3400N). For the manual transfer methods peak compressive forces greater than 10,000 N were predicted, which far exceeded the NIOSH upper limit of 6400 N. When mechanical lift devices were used, the back compression forces were below the back compression design limits. This study reinforces the need to utilize a mechanical lift device when transferring totally dependent patients with only two nurses.