Exposure to the particulate matter is related to a variety of acute and chronic health effects. Also, it is an important factor in the indoor air quality in hospitals. The present study aimed to determine the effect of meteorological parameters on the indoor PM2. 5 and PM10 concentrations in the operation room, pediatric, and intensive care unit wards in the hospital in Kashan, Iran. The PM2. 5 and PM10 concentrations were measured at two indoor sites and one outdoor site in each one of the wards from March to May 2015. Also, the wind rose was drawn for determining the Prevailing wind. The mean indoor and outdoor PM2. 5 and PM10 concentrations increased during the study period. The results obtained of wind rose showed that the prevailing wind (4. 5% of the entire winds) was the direction of the west-southwest. Also, the highest mean outdoor PM2. 5 and PM10 concentrations were related to the ambient wind directions of the east-northeast, the west, and the north-northwest in the operation room, pediatric and intensive care unit wards, respectively. According to the findings, there was a positive association between the indoor and outdoor PM2. 5 and PM10 concentrations in the wards. Also, the meteorological parameters played an important role in the indoor particle mass concentrations in the study wards in the hospital. The effective meteorological parameters on the particle concentrations were the ambient temperature, wind speed, relative humidity, and rainfall in the hospital. It is asking for improving the indoor air quality of managers and officials to protect the patients and staff against transferred diseases by the particles in the wards in the hospital.