The main objective of this study was to estimate the seroprevalence of Bovine herpes virus type 1 and
parainfluenza type 3 in a non-vaccinated population cattle in the livestock region of Qazvin province.
Totally 504 sera were randomly collected and tested from 8 industrial dairy farms in Qazvin province
during March 2010-March 2011. The result of one way analysis of variance was used for the analysis data.
Also Tukey Method was employed to detect pair wise differences among the ages determined that there
were a significant differences among the average titer in 1 to 3, 1 to 4, 2 to 3 and 2 to 4 year cows (P