This paper describes two field studies of thermal comfort conducted in Ilam, a city located in western Iran. The first study consisted of two short-term surveys carried out during two climatically extreme periods-a hot summer and a cold winter-in 1998. The second study consisted of a long-term survey that collected data throughout the whole of 1999. Both studies were performed in naturally ventilated buildings. This paper shows some comparative analysis between the findings from the short-and long-term studies. For the hot season the neutral temperatures from the short-and long-term studies were 28.4 and 26.7 degreesC, respectively. For the cold season the short-and long-term neutral temperatures were 20.8 and 21.2 degreesC, respectively. The results show a very good agreement between both studies in Iran. The main points of interest from the studies were the variability of acceptable conditions, a good relationship between neutral temperature and room temperatures and also, more importantly, between indoor comfort and outdoor conditions. The findings reveal that the people in the study could achieve comfort at higher indoor air temperatures compared with the recommendations of international standards such as ISO 7730.