Objectives:To estimate the effect of improved stoves on the prevalence of ARI and conjunctivitis among children aged below five years and women aged between 15 and 60 years. Method: A field trial or intervention study design, in which cluster and random sampling were used to recruit households with improved stoves. Nearest households with traditional three-stone stoves were recruited as controls. Prevalence of ARI and conjunctivitis among the study subjects was estimated by clinical evaluation and physical observation, and by history (including clinical and socioeconomic information), and compared between the two study groups. Results: The prevalence of ARI among children aged below five years and among women aged between 15 and 60 years were significantly higher in households with the traditional three-stone stoves than in those with the improved stove χ2 =31.45 ρ = 0.00000, relative risk = 2.6, C.l. 1.86,3.63, and χ2 = 30. 13, ρ = 0.00000, Relative Risk = 2.8, C.l. 1.93, 4.06, respectively). Similarly the prevalence of conjunctivitis among children aged below five years and among women aged between 15 and 60 years were significantly higher in households with traditional three-stone stoves than in those with the improved stoves (c2 = 24.18, p = 0.00000, Relative Risk = 3.3, C.l. 2.05,5.32, and χ2 = 7.6, ρ = 0.0057, Relative Risk = 3, C.I. 1.38, 6.54. respectively). Conclusion: Prevalence of ARI and conjunctivitis among children aged below five years and also among women aged between 15 and 60 years in households with the traditional three-stone stoves was significantly higher than that in households with improved stoves.