For swimmers, exposure to chloroform, a probable carcinogen, in indoor swimming pools can be through different pathways such as ingestion, dermal absorption, inhalation during swimming, and inhalation during resting. In order to evaluate health risk results from excessive exposure to chloroform, concentrations of chloroform in pool water were first collected and analyzed. Then, a two-layer model is used, which is capable of estimating the concentrations of chloroform in the boundary layer adjacent to the water surface and the concentrations of chloroform in indoor swimming pool air. The use of stratification model is important for estimating the risks for swimmers since they are exposed to these kinds of situations while performing swimming and resting in indoor swimming pools environment. The incremental lifetime cancer risk (ILCR) was then estimated using the multi-pathway exposure model. The results showed that the 95th percentile of ILCRs calculated for male and female swimmers were 2.80 x 10(-4) and 2.47 x 10(-4), respectively. The major exposure routes were found to be inhalation during swimming which contributes to more than 99% of the total health risk. Our study suggested that to protect swimmers from excessive exposure to chloroform, alternative methods or processes of disinfection should be considered for swimming pool managers. (C) 2010 Elsevier B.V. All rights reserved.