Background and aims: The main objective of immunization by hepatitis B vaccine is to generate adequate concentration of anti hepatitis B antibody (HBsAB) in the serum. This study was aimed to determine the effectiveness of hepatitis B vaccination campaign in 18 years old students in Chaharmahal va Bakhtiari province. Methods: In a cross- sectional study, 360 students with 18 years old (born in 1989) and have taken 3 doses of hepatitis vaccine in national vaccination campaign in 2007, were selected by cluster sampling. This study was performed in 2008 in Chaharmahal va Bakhtiari province in the central of I.R of Iran. The level of hepatitis B antibody was detected by quantitative ELIZA method using Dialab Kit. The collected data was analyzed using SPSS 16.0 software by X2 and t-test. Results: Of 360 students, 164(45%) cases were male and 174 (48/3%) cases were from urban areas. Just 349 students (96/95%) have acceptable immunization responses, (In those anti hepatitis B antibodies were more than 20 IU/ml). There was no significant relationship between the level of antibody and variables such as: sex, born places, smoking, contact history, previous disease and Hejamat (P>0.05). Conclusion: Considering the results of the present study and previous researches from others countries, we can emphasize that the mass vaccination has been effective in those 18 years old students and we can be sure that the vaccination has been performed perfectly in Chaharmahal va Bakhtiari province
