Radiotracer methodology applied to troubleshooting and process improvement provide substantial economic benefits in petroleum refining. The benefits derive from rapid identification of operating problems, reduction of unscheduled shutdowns or shorter downtime; and improvements in processing operations, operating efficiency, product quality and yield. The costs for performing tracer studies is small compared to the benefits obtained. Refinery examples are given and the benefits are expressed in dollars wherever possible. Wider use of this technology promises greater benefits throughout all industry.