Extensive field surveys were conducted to collect Pierid butterflies and their host plant flora from all districts (Jhelum, Rawalpindi, Chakwal, Attock, and Islamabad) of Potohar region of Punjab Pakistan during January 2012 – February 2015. A total of 1839 specimens belonging to 19 species were identified under two subfamilies and ten genera. The identified species were Catopsilia pyranthe, C. crocale, C. pomona, Gonepteryx mahaguru, G.rhamni, Colias fieldii, C. erate, Eurema laeta, E. hecbae, Delias eucharis, Pontia daplidice, Belenois aurota, Pieris rapae, P. canidia, P. brassicae, Ixias pyrene, Colotis amata, C. etrida, and C. protactus. Among these, eight (08) species; Delias eucharis, Belenois aurota, Pieris rapae, Colotis amata, C. etrida, Gonepteryx mahaguru,G.rhamni and Colias erate were reported for the first time from Potohar region. The current study as being first biogeograhical study from Potohar region recognizes the elements from all biogeographical regions of the world. However, the Afrotropical and the Aust- oriental elements remain dominant. Among reported host plants, 21 species of 15 plants [Capparis aphylla, (family Capparaceae), Cassia fistula, Sesbania grandiflora (family Fabaceae), Salvadora oleoide (family Salvadoraceae), Loranthus longiflorus, Scurrula pulverulenta, (family Loranthaceae), Rhamnus triquetra, R. purpurea (family Rhamnaceae), Brassica napus, B. oleraceae, B. oleraceae var. italica, B. campestris, B. officinalis, Raphanus sativus, Eruca sativa (family Cruciferae)] are new records for Pakistan, However six (06) host plants [Lepidium pinnatifidium, Coronopus didymus, Arabidopsis thaliana (family Cruciferae), Cassia occidentalis, Medicago sativa, and Melilotus officinalis (family Fabacae)] are new addition to world''s host plant list of Pierids fauna. GIS map distribution of all the butterflies along with their host plants is provided for the first time from pakistan.Taxonomic keys for subfamilies, genera and species were also prepared. From the study area, the complete list of host plants of family Pieridae up to species level has been provided first time. In the present study, relative abundance and percentage of different butterflies were found in each district. In district Jhelum, Pieris brassicae showed highest relative abundance (0.18) and percentage (18.12), with its host plant Brassica oleraceae (0.25) and percentage (25) respectively. In district Rawalpindi, xvii Pontia daplidice showed highest relative abundance (0.20) and percentage (20.05) with its host plant Lepidium pinnatifidium (0.28) and percentage (28). In the districts Attock and Chakwal, Catopsilia pomona showed highest relative abundance (0.19) and percentage (18.99) with host plant Coronopus didymus (0.38) and percentage (38) and Lepidium pinnatifidium, Brassica napus, Brassica compestris (0.16) and percentage (16). In district Islamabad, Pieris canidia showed highest relative abundance (0.23) and percentage (23.22) with its host plant Coronopus didymus (0.28) and percentage (28). Diversity of Pierids butterflies and their host plants was calculated by using five diversity indices namely; Simpson, Shannon, Evenness, Menhinick, Margalef and Equitability. The values from five districts of Potohar region were within suitable range of Simpson index i.e. between 0.8-0.9 for butterflies species and host plant which shows their stable community in the region. However, Shannon and Weiner values of five districts revealed that Potohar region has rich host plant flora and butterfly fauna with even distribution as most of values were between 1.8 and 2.4. In Potohar region, the values of evenness index ranges between 0.5-0.8 which shows even distribution of butterfly''s species and host plants in the region. The overall calculated values of Menhinick index of butterfly''s species were between 0.5- 0.7 which showed high diversity of butterfly''s species and host plants within the region. The Margalef and equitable index values showed high species richness for butterflies and host plants in the region. Highest species richness were recorded in Rawalpindi and Islamabad districts (2.336-2.023) and comparatively low species richness were recorded in district Attock (1.516) and for the host plants highest specie richness were recorded in the same 2 districts i.e. 1.83 and in Rawalpindi and Islamabad.