A follow-up study in two rural communities in the state of Chiapas, Mexico, compared families that used an improved stove for cooking with those that used traditional open-fire stoves, to assess the risks of respiratory symptoms in children and women exposed to wood smoke. 16-hour measurements showed that the concentration of particles less than 10 microm in diameter was significantly lower in households with the better stoves in the kitchen area, where children usually play, i.e., 158 microg/m3 vs 305 microg/m3 (p = 0.03). Multivariate models showed that using the better stove tended to protect against symptoms such as the common cold in children (RR 0.24; 9.5% CI 0.05, 1.02). Use of more firewood was linked to greater risks of experiencing difficulty breathing (RR 1.15; 95% CI 1.04, 1.27) and the common cold (RR 1.09; 95% CI 1.01, 1.18) in women. The use of stoves that require less wood for cooking reduces the risks of respiratory symptoms that may contribute to complicated respiratory diseases and mortality.