We studied the survival of 195 patients with agnogenic myeloid metaplasia (AMM) diagnosed between 1962 and 1992 in an attempt to stratify patients into risk groups. Median survival was 42 months. Adverse prognostic factors for survival were age > 60 years, hepatomegaly, weight loss, low hemoglobin level (Hb), low or very high leukocyte count (WBC), high percentage of circulating blasts, male sex, and low platelet count. A new scoring system based on two adverse prognostic factors, namely Hb < 10 g/dL and WBC < 4 or > 30 x 10(9)/L, was able to separate patients in three groups with low (0 factor), intermediate (1 factor), and high (2 factors) risks, associated with a median survival of 93, 26, and 13 months, respectively. An abnormal karyotype (32 cases of 94 tested patients) was associated with a short survival, especially in the low-risk group (median survival of 50 v 112 months in patients with normal karyotype). The prognostic factors for acute conversion were WBC > 30 x 10(9)/L and abnormal karyotype. Thus, hemoglobin level and leukocyte count provide a simple prognostic model for survival in AMM, and the adverse prognostic value of abnormal karyotype may be related to a higher rate of acute conversion.