Given the observed association between KIR gene polymorphisms and MTCT reported in non-malaria endemic area in South Africa [26, 27] and a possible interaction between MTCT and malaria infection in pregnant women, we conducted a pilot study to investigate the relationship between MTCT and KIR gene content polymorphisms in mother-child pairs from western Kenya where co-infection of HIV with malaria is very common. Here, KIR3DL1 is linked to coinfection.