Construction workers are at increased risk for fatal and non-fatal injuries. This study examined the effectiveness of employee orientation and training in reducing injuries among plumbers and pipefitters. We searched the Occupational Safety and Health Administration's "recordable" injury data and "documentable" safety and training records for six plumbing and pipefitting employers in northwestern Ohio. During the period 1996 to 1998, 133 injuries were recorded with the duration of 2,541,432 working hours. The most common types of injuries were cuts, lacerations, and abrasions. The majority of injuries resulted from workers being struck by objects. The injury rate was significantly higher for small companies and longer working hours. No difference was found between traveling and local workers. Seventy-five percent of workers received safety orientations on injury prevention. Among workers who received safety orientations, only 3.4% experienced injuries, compared with 11.1% of workers without orientations. Safety orientations were associated with a significant reduction in injuries (odds ratio, 0.23; 95% confidence interval, 0.15 to 0.35). Proper safety orientation and training could reduce the risks for occupational injuries in construction workers.