PID controllers are being widely used in industrydue to their well-grounded established theory, simplicity,maintenance requirements, and ease of retuning online. In thepast four decades, there are numerous papers dealing withtuning of PID controller. Designing a PID controller to meetgain and phase margin specification is a well-known designtechnique. If the gain and phase margin are not specifiedcarefully then the design may not be optimum in the sense thatcould be large phase margin (more robust) that could give betterperformance. This paper studies the relationship between ISEperformance index, gain margin, phase margin and comparestwo tuning technique, based on these three parameters. Thesetuning techniques are particularly useful in the context ofadaptive control and auto-tuning, where the control parametershave to be calculated on-line.