Forestry workers are exposed to harsh environmental conditions, awkward postures, and high intensity load handling that might lead to low back injuries. The objectives of our study were 1) to define the trunk postures associated with risk of low back injury in a sample of forestry workers involved in tree felling, delimbing and bucking tasks and 2) to identify prevention strategies that reduce the risk of low back injury. Forty loggers were selected among the population of forestry workers in the province of Enna, Sicily-Italy. Each worker was required to perform for a period of 30 minutes the three main tasks: felling, delimbing and bucking for a total of 90 minutes of working activity. All subjects involved in the study wore a Zephyr Bioharness device on their trunk, which enabled the recording of sagittal inclination of the trunk, heart rate, breathing rate, and an estimate of body temperature. The results indicated that the felling task required loggers to work more time in awkward postures. Additionally, sagittal inclination of the trunk was greater than 60° for the 13% of the time, compared with delimbing (3%), and bucking (11%). The percentage of time spent with the trunk in sagittal inclination greater than 60° was correlated with the use of heavy (> 7,2 kg) chainsaws during the felling and in the delimbing tasks. The study results indicated that the trunk posture during tree delimbing and felling tasks contributed significantly to the risk of biomechanical overload among the loggers. Preventive strategies should focus on specific interventions that reduce biomechanical stress including worker training and implementation of ergonomic designed tool.