Since few studies focus on prognostic factors in unselected elderly acute myeloid leukemia (AML) patients, a retrospective analysis of 138 consecutive patients aged >55 years (median age: 67, range: 56-89) with AML diagnosed at a single center over an 8-year period was performed: 69% had de novo AML and 31% secondary (s) AML; 67% of the patients were karyotyped. Of the patients, 73 (53%) were treated with standard induction therapy protocols and 65 (47%) received palliative treatment only. Univariate and multivariate analyses of the effects of the following factors on overall survival (OS) were performed: sex, age > or = vs <65 years, de novo vs sAML, serum (s) lactate dehydrogenase (LDH) > or = vs <400 U/l, leukocytes > or = vs <50,000/ microl, induction therapy, and karyotype. Additionally, in patients receiving induction therapy, complete remission (CR) rates and survival from CR were analyzed. CR rate was 47% [95% confidence interval (35%, 59%)], 53% (39%, 66%) in de novo AML, and 21% (5%, 51%) in sAML. After a median follow-up of 4 years, 130 deaths were observed (94%). In a univariate analysis, significant factors for longer OS were induction therapy, age <65 years, sLDH <400 U/l, and de novo AML. In a multivariate analysis, significant factors for longer OS were sLDH <400 U/l and induction therapy. However, the difference between treatment outcome may also be due to selection criteria not captured, such as performance status, comorbid conditions, wish of the patient, etc. The effects of intensive and nonintensive treatment in this patient group need to be investigated in prospective, randomized trials in which these clinical parameters of high relevance for treatment decisions in older patients are also considered.