The present study analyses the difficulties that may be faced by the smokers that take part in a self-help treatment for smoking cessation, potentially leading to the non-fulfilment of the treatment tasks. The study analyzed the tobacco quit process in a sample of 100 smokers who participated in a self-help treatment for smoking cessation. The results obtained show that the most common difficulties faced by smokers are related with the following tasks: reduction of number of cigarettes; let a part of the cigarette without smoking; accomplishing the self-reports; reading the manual; changing brands when indicated; non smoking in several situations; maintaining a waiting period before smoking, after meals and/or coffee; and starting the treatment. Futhermore, it is observed that such difficulties are the product of mainly two factors: the absence of an adequate reading of the manual, and the underestimation of the relevance of some tasks indicated throughout the treatment.