The paper presents a pole-zero diagram which is applicable to m.t.i. radar filters operated with a staggered p.r.f. Such a diagram is readily constructed from the pulse transfer function of the filter, and may also be used when time-varying coefficients are employed. It enables the potential performance of a given filter to be quickly assessed, and affords the designer a convenientmethod of obtaining optimum stopband performance from staggered p.r.f. filters without the use of computer optimisation techniques.