Thirty-eight nursing assistants (NAs) in a nursing home ranked and rated 16 different patient handling tasks for perceived stresses to the low back. The nursing assistants were observed for 79 4 h shifts and were videotaped for 14 4 h shifts to describe a typical workday and to determine the number of patient-handling tasks performed per shift, the use of assistive devices, and biomechanical stresses to the low back. In addition, data were collected on nursing assistants' and patients' characteristics. The top eight ranked tasks included transferring patient from toilet to wheelchair (WC), WC to toilet, WC to bed, bed to WC, bathtub to WC, chairlift to WC, weighing patients and lifting patients up in bed. The mean ratings of perceived exertion for these tasks were between 'somewhat hard' and 'hard'. The estimated compressive force on L5/S1 disc for the 50th percentile patient weight ranged from 3.7 to 4.9 KN. Nursing assistants worked in teams of two and performed 24 patient transfers per 8 h shift by manually lifting and carrying patients. Assistive devices (a hydraulic lift and gait belt) were used less than 2% of the time. Patient safety and comfort, lack of accessibility, physical stresses associated with the devices, lack of skill, increased transfer time, and lack of staffing were some of the reasons for not using these assistive devices. Environmental barriers (such as confined workplaces, an uneven floor surface, lack of adjustability of beds, stationary railings around the toilet, etc.) made the job more difficult. Nursing assistants had a high prevalence of low-back pain and 51% of nursing assistants visited a health care provider in the last three years for work related low-back pain.