Introduction Malaria kills a large number of children each year. 1 In 2012,482,000 children under the age of five died from Malaria worldwide. 1 While 90% of these deaths occurred in Sub-Saharan Africa, malaria also poses a significant threat to children in Pakistan where it is endemic. 2 According to WHO, Plasmodium vivax (P vivax) and Plasmodium falciparum (P falciparum) causes 75% and 25% of malaria in Pakistan respectively. 3 In 2011, 319,592 confirmed cases of malaria were reported. 4 As only 71% of the population uses public sector hospitals, the total disease burden in general and in children specifically is likely to be much higher. 5 Chloroquine sensitive P.vivax is the major causative parasite of malaria in children and adults in Pakistan. WHO recommends chloroquine as a first line therapy for uncomplicated vivax malaria. However, doctors seldom comply to WHO's guidelines and artemisinin (ACTs) based combinations are used for its management. 6 Although Pvivax remains the leading cause of malaria in Pakistan (67%), its resistance pattern has not been characterized. 7 Many studies have assessed the treatment of malaria in children from various small districts and localities of Pakistan but there is no recommendation for the use of ACTs across the board here. Though some cases of resistance to chloroquine in P vivax have been reported from Bannu, 8,9 (a small district in North Western Province of Pakistan) and some anecdotal isolated cases reported from Sind and Baluchistan province, WHO still recommends chloroquine as a first line therapy. 4 ACTs are only recommended for malaria in parts of Latin America and isolated pockets of East Asia where P vivax is resistant to chloroquine. Currently Pakistan and Afghanistan are not amongst regions with comparable or high resistance pattern. 10,11 Furthermore, Khattak et al have shown with molecular markers that in Pakistan chloroquine resistance to Pvivax has not yet surfaced but some mutations may pose future risk 7 which may be compounded with unjustified treatment of malaria by non-adherence to WHO guidelines. 7 Our study re-emphasizes the need to treat uncomplicated Pvivax malaria with chloroquine in accordance with the guidelines proposed by the MCPP and WHO. We feel that unnecessary use of ACTs could contribute to possible emergence of artemisinin resistant strains of Pvivax. J Pak Med Assoc 30 ORIGINAL ARTICLE Efficacy of Chloroquine as a first line agent in the treatment of uncomplicated malaria due to Plasmodium vivax in children and treatment practices in Pakistan: A Pilot study Talal Waqar, 1 Arshad Khushdil, 2 Khalid Haque 3 Abstract Objectives: To ascertain the efficacy of chloroquine as first line agent in treatment of uncomplicated malaria - caused by Plasmodium vivax in children---and to determine its current treatment practice in Pakistan. Methods: This pilot study was conducted at the Paediatrics Department of Combined Military Hospital (CMH), Lahore, Pakistan. Forty-eight children between six months and twelve years of age having positive blood film for Plasmodium vivax were included. They were treated with chloroquine as a drug of - choice. Efficacy of chloroquine was assessed by clinical response, absence of parasitaemia on day seven and twenty-eight after initiation of therapy. A survey was also conducted to determine the first line therapeutic choice of Paediatricians in the treatment of uncomplicated Plasmodium vivax malaria in children in Pakistan. Results: The results showed 100% efficacy of chloroquine in treating uncomplicated malaria caused by Plasmodium vivax in children. Artemisin was preferred by 74.28% Paediatricians' in combination therapy as 1st line treatment. Conclusions: Guidelines proposed by Malaria Control Programme Pakistan (MCPP) in collaboration with World Health Organization (WHO) are comprehensive but not being adhered to. The recently reported resistance of Plasmodium vivax to artemisin should urge measures to implement WHO guidelines. Keywords: Vivax malaria, chloroquine, Pakistan, WHO. (JPMA 66: 30; 2016) 1 Department of Paediatrics, CMH, Rawalpindi, 2 Department of Paediatrics, CMH Skardu, 3 Retd. Prof of Neonatal Medicine, San Francisco, USA. Correspondence: Talal Waqar. Email: talalwaqar@yahoo.co.uk