Between January and April 2005, NIOSH received confidential requests for HHEs from nonpoker (NP) casino dealers at Bally’s, Paris, and Caesars Palace casinos in Las Vegas, Nevada. These casino dealers were concerned that exposure to ETS in their workplace was causing a variety of acute and long-term health effects. In response to these requests, NIOSH investigators conducted three onsite evaluations at Bally’s, Paris, and Caesars Palace casinos. The first onsite evaluation was conducted July 22-24, 2005, during which we interviewed employees, reviewed OSHA Forms 200 and 300 (Log of Work Related Injuries and Illnesses), and administered a screening questionnaire. The screening questionnaire was used to select potential participants to take a subsequent health symptom questionnaire and undergo environmental and biological monitoring. During the second site visit, from August 21-24, 2005, additional screening questionnaires were distributed to NP casino dealers. A health symptom questionnaire was mailed January 6, 2006, and we conducted biological and environmental monitoring on our final site visit from January 19-22, 2006. During the confidential medical interviews and the open discussions, NP casino dealers reported that they were most concerned about respiratory health effects related to ETS. NP casino dealers who worked in areas where smoking was permitted made up our study sample. Casino employees in administrative and engineering jobs who worked in areas where smoking was not permitted made up the comparison group. Of the responses from the health symptom questionnaire, the three most common symptoms reported by NP casino dealers were red or irritated eyes, cough, and stuffy nose. The prevalence of upper and lower respiratory symptoms, eye symptoms, headache, nausea, and dizziness was higher among the NP casino dealers than among the administrative and engineering employees, but these differences were not statistically significant. The low participation rate of the NP casino dealers and the small number of administrative and engineering casino employees may limit our ability to provide a confident estimate of symptom prevalence among these groups. Of the 1,188 total poker and NP casino dealers working in Bally’s, Paris, and Caesars Palace, 124 NP casino dealers participated in the environmental and/or biological exposure assessment. Full-shift personal breathing zone (PBZ) and area air sampling for nicotine (NIC), respirable suspended particulates (RSP), volatile organic compounds (VOCs), polynuclear aromatic hydrocarbons (PAHs), and aldehyde (ALD), were conducted in the casino gaming areas on Thursday, Friday, and Saturday during the swing shift and on Sunday during the day shift at all three casinos. We also monitored carbon monoxide (CO) in the area samples. NIC PBZ concentrations were similar to ranges found in a previous study of ETS in a casino. Of the 16 PAHs monitored, only naphthalene was present in quantifiable amounts. The VOCs identified included benzene, toluene (TOL), total hydrocarbons, p-dichlorobenzene, and limonene. The overall geometric means of the area samples were similar to those of the PBZ samples. Area CO concentrations were very low, with maximum values for each day measured ranging from 0.8-5.3 ppm in the three casinos. We collected preshift and postshift urine samples on 114 NP casino dealers to determine whether levels of ETS biomarkers (Cotinine (COT) and 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL)) in their urine would increase over an 8-hour work shift. Levels of NNAL in urine increased significantly during an 8-hour work shift both adjusting for, and not adjusting for, creatinine clearance. Creatinine-unadjusted COT increased during the 8-hour shift, but creatinine-adjusted COT decreased. The NP casino dealers at Bally’s, Paris, and Caesars Palace casinos had measurable airborne levels of ETS in their personal breathing zone and were found to absorb an ETS component into their bodies, as evidenced by measureable levels in the urine. The presence of NNAL in the urine demonstrates that casino dealers are exposed to a known carcinogen from the tobacco smoke. NP casino dealers reported higher prevalence of respiratory symptoms compared to administrative and engineering employees, but the differences in the prevalence between the groups were not statistically significant.