Our retrospective study was aimed at assessing parameters affecting the prognosis of acute non lymphoid leukemia (ANLL). Since 1988 to 1994 we observed 84 patients: 52 males, 32 females. For each patient we considered at diagnosis: age, fever, performance status, platelets, hemoglobin and white blood cell count, extramidollary disease, bone marrow blastosis, phenotype and cytogenetic abnormalities of blasts cells. All the parameters listed above were correlated with the time to achieve the complete remission (CR), CR duration and the overall survival. Statistical tests as t-student and chi square test were used. Statistical analysis of the parameters considered revealed that the only value affecting the achievement of a CR was the age. The prognostic significance of immunophenotyping in ANLL has been a controversial issue, with a number of conflicting reports. In our study only the terminal deoxynucleotidyl transferase was significantly associated with prognosis. Our study, as data reported in literature, confirms that the prognostic impact of the various parameters in ANLL is controversial. The study of prognostic factors and of the immunophenotype is important to identify the clinical and the biologic profile of the disease and to evaluate the optimal post-remission treatment.