There is evidence that stimulants such as alcohol and tobacco have an effect on the immune system, but little is known about how these lifestyle factors affect the prevalence of contact sensitization. This study investigated whether smoking and alcohol consumption were associated with contact sensitization and nickel sensitization. A random sample of adults (n=3460) from the general population of Copenhagen was invited to participate in a general health examination including patch-testing. Alcohol consumption was not associated with nickel sensitization, whereas a significant trend (p<0.05) was identified between smoking status and nickel sensitization in an adjusted model; i.e. nickel sensitization was higher among both previous smokers (odds ratio (OR) = 1.19; confidence interval (CI) = 0.81-1.76), current light smokers (OR=1.50; CI=0.94-2.37) and current heavy smokers (OR=1.56; CI = 0.87-2.80) compared with never smokers. This study confirmed that smoking is associated with nickel sensitization, but rejected an association with alcohol consumption.