Advance directives (ADs) might be useful in achieving improved communication and satisfaction with decision making at the end-of-life. Our aims were to better characterise patients with advanced oncological disease who decided to complete ADs and to measure the effect of ADs completion on the satisfaction level with end-of-life care from both patients and their relatives. A prospective study was conducted in three palliative care units. Patients with advanced cancer were included if they met the following criteria: an estimated life expectancy of <6 months, fluency in French, Mini Mental State Examination >20 and not yet completed ADs. All the patients received information about ADs and decided whether to complete ADs or not. The level of satisfaction with involvement in the decision process concerning end-of-life care was assessed by means of a written questionnaire. In all, 53 of 228 patients were included, and 12 decided to complete ADs. Patients who completed ADs had statistically less depression one week after inclusion (P = 0.030), had a lower anxiety score on the second week and had a lower depression score on the third week. There was a trend towards a higher satisfaction level with the involvement of the patients in end-of-life care for those completing ADs (P = 0.878). In conclusion, each patient with an advanced progressive disease should be informed about ADs and be encouraged to complete the ADs with the aim to ease many fears as well as to improve communication.