Quantitative estimate of there sponse of ionization chamber based pocket dosimeters (DRDs) to various beta sources was performed. It has been established that the ionization chamber based pocket dosimeters do not respond to beta particles having energy (E_max) o1 MeV and same was verified using ¹⁴⁷Pm, ⁸⁵Kr and ²⁰⁴Tl beta sources. However, for beta particles having energy >1 MeV,  the DRDs exhibit measureable response and the values are ~8%, ~14% and ~27%permSvfornatur aluranium, ⁹⁰Sr/⁹⁰Y and ¹⁰⁶Ru/¹⁰⁶Rh beta sources respectively. As the energy of the beta particles increases, the response also increases. The response of DRDstobetaparticleshavingenergy41 MeV arises due to the fact that the thickness of the chamber walls is less than the maximum range of beta particles. This may also be one of the reasons for disparity between doses measured with passive/legal dosimeters (TLDs) and DRDs in those situations in which radiation workers are exposed to mixed field of gamma photons and beta particles especially at uranium processing plants, nuclear (power and research) reactors, waste management facilities and fuel reprocessing plants etc. The paper provides the reason (technical) for disparity between the doses recorded by TLDs and DRDs in mixed field of photons and beta particles.