Background:
Perceptions of smoking-related health risks and benefits among young adults (18–24 years) and their smoking behaviour have not been adequately studied in low-income countries like Nepal. This study has examined the perceived risks and the benefits of smoking among young adults who smoke vs. don’t smoke.

Methods:
A cross-sectional study was carried out from August to September 2013 among 315 young adults (18–24) from four conveniently selected private colleges of different faculties in Kathmandu Metropolis. The anonymous, self-administrated and semi structured questionnaire contained the information on individual information; smoking behaviour; and perceptions on smoking-related risks and benefits. Kaplan-Meier analysis was used to identify the mean age of smoking initiation. Cox proportion hazard regression was used to assess the relationship between current smoking behaviours and the perceived risks and the benefits of smoking.

Results:
Overall, the prevalence of current smoking was 16.2 % (Male =28.4 % and female =5.38 %). The mean age of smoking initiation was 16.6 and 17.7 years for male and female respectively. The risk of becoming a current smoking being a management student was higher (HR = 4.72, 95 % CI: 2.19; 10.20) than being a medical student. The risk of current smoking behaviour significantly increased with those who believed that smoking was enjoyable (HR = 4.74, 2.58; 8.72); would help to deal with problems or stress (3.19, 1.76; 5.79); would feel comfortable with friends (4.29, 2.33; 7.92); would be relaxing (6.95, 3.60; 13.43); and something to do when feel bored (3.42, 1.91; 6.13). The young adults who believed that smoking would make yellow teeth (0.53, 0.30; 0.94) and yellow nail (0.53, 0.29; 0.95); and would be bad to their health (0.45, 0.21; 0.98) were significantly at lower risk of becoming a current smoking.

Conclusions:
Positive perceptions related to smoking are common among young adults. To discourage smoking, future intervention programs should focus communicating not only health risks but also counteract perception of benefits related to smoking.