Few studies examine predictors of smoking cessation among medically ill smokers, despite their high smoking prevalence. We prospectively examined barriers to smoking cessation in medically ill smokers, with age as a hypothesized moderator. Participants were smokers (N = 237, M
age = 56.1, 53.6% females) receiving home-based nursing care. Baseline self-report questionnaires assessed barriers to cessation (demographics, smoking history, psychosocial, and medical factors). Smoking status was biochemically verified at 2- and 6-months post-intervention. Compared with younger smokers, older smokers had significantly lower levels of nicotine dependence, stress, and depressed mood and a greater prevalence of smoking-related diseases. Older smokers were more likely to achieve biochemically verified abstinence at 6-month follow-up (7.8%) than younger smokers (3.1%) though this difference was not significant. Higher levels of depressed mood and lower levels of perceived stress were associated with a greater likelihood of cessation at both follow-up points, but only for younger smokers. For younger smokers, higher self-efficacy to quit and the presence of a smoking-related disease increased the odds of abstinence. These findings could help guide treatment development for this high-risk group of smokers.