The dielectric dispersion of the solid solutions (Pb1-xBa x)(Zn1/3Nb2/3)O3 and (Pb 1-xSrx)(Zn1/3Nb2/3)O3 with x = 0.2 and 0.3 has been studied as a function of temperature for the frequency range 0.1 to 200 kHz. The variation in the relaxor nature between the studied compounds is discussed using the generalized Curie-Weiss law. The paper also discusses the variation in the relaxation mechanism in these compounds with Barium and Strontium substitution using Vogel-Fulcher relation and power law. Detailed analysis of power law shows that Barium substituted Pb(Zn 1/3Nb2/3)O3 exhibits stronger dielectric relaxation than Strontium substituted Pb(Zn1/3Nb2/3)O 3.