The first work-related characteristic associated with LBP occurrence was the length of the workday. Persons working more than 8 hours a day showed higher prevalence of LBP. To our knowledge, this is the first study to demonstrate an association between long working hours and LBP in textile fish net manufacturing. Regarding other work characteristics, multiple logistic regression was used to identify significant factors while controlling for potential confounding effects of individual variables. Results revealed work characteristics associated with the 7-day prevalence of LBPs to include standing and walking during work, stooping, lifting, and high concentration jobs. Results indicated that LBP was primarily associated with standing and walking. Conversely, several previous studies on associations of standing posture and walking with LBPs found insignificant correlations (Engels et al., 1996; Harkness et al., 2003; Yip, 2004). However, Pope et al. (2002) explained that muscular activity is required to maintain equilibrium when shifting the center of gravity of the trunk, head, and upper extremities, as in walking. Moreover, our findings showed that age group was an effect modifier of the association of standing and walking with LBP. The adjusted OR values for groups of workers whose age was less than 35 or was 35 years or greater, were 4.9 and 1.7, respectively. From our analyses, workers less than 35 year of age were more likely to be at risk of LBP due to standing or walking (71 vs. 26%) than the older group. This finding may seem counter to the general finding of increased LBP for older workers. The primary reason for this result is that the occurrence of LBP for older workers in tasks not involving standing or walking was generally higher (59%) and was substantial relative to the number of older workers experiencing LBP when required to stand or walk (76%). With respect to explaining increased reporting of LBP among the younger workers,Althoff et al. (1992) demonstrated that the soft tissues around the spine were significantly deformed in young versus older people after prolonged standing or walking. Therefore, it is possible that the difference in the rate of LBP for young workers who worked in a standing posture or while walking versus that of those who did not was much greater than the difference in the rate of LBP for the aged group in work with and without standing and walking.