Background: Genotype announcements related to susceptibility to hazardous effects of smoking may be effective to induce smoking cessation. Methods: Subjects were municipal government employees, 63 young smokers employed in the previous year and 59 smokers with more than 45 pack-years, who were invited to educational sessions against smoking held in December 2003 and February 2004, respectively. In the session, those who wished genetic susceptibility tests (GSTM1, GSTT1, and NQO1 C609T) were enrolled in the study. The smoking habit was ascertained three times: at the session, one month later, just before the genotype announcement, and at the follow-up three months after the announcement. Results: Fifty eight (92.1%) and 49 (83.1%) smokers participated in the study, respectively. One out of 58 smokers was not a habitual smoker, so was not included in the analysis. The smoking cessation rates were 15.8% (9 participants) and 6.1% (3 participants) just before the genotype announcement, and 7.0% (4 participants) and 10.2% (5 participants) at the follow-up, respectively. All subjects were satisfied with the genotype testing except for two who rather regretted participating, but one of whom actually quit smoking. Conclusion: The present pilot study without controls indicated that the effects of genotype announcements in this framework on smoking cessation were less than might have been expected. The temporary effect of the session on younger smokers may have been due to the participation per se. The potential effects of genotype announcements for heavy smokers should now be examined in studies with adequate controls.