The manifestations and outcome of adult patients with acute leukemia (AL) were examined to study the characteristics of the rheumatological prodrome of AL and to find whether it is a marker of a distinct clinical and laboratory course and whether it has any prognostic implication. During a 10-year period, 8/139 (5.8%) of AL patients presented with rheumatic manifestations. The average duration of the arthritis syndrome preceding the diagnosis of AL was 3.25 months. The most common pattern of presentation was a reactive arthritis-like syndrome involving the large joints asymmetrically and associated with low back pain. Distinctive features suggesting a paraneoplastic arthritis were severe pain disproportionate to physical findings, a poor response to conventional antirheumatic treatment, and early significant osteopenia or lytic bone lesions. The epidemiological, clinical and laboratory characteristics of patients with or without rheumatic manifestations were comparable, except for fever on presentation, the presence of transient metabolic derangement following chemotherapy, and the initial average hemoglobin, hematocrit and serum uric acid values. Moreover, the initial outcome of the two groups was similar, as the early mortality rates were comparable (42.8% vs. 45% for patients with or without arthritis, respectively). In conclusion, rheumatic syndrome presentation of adult AL is uncommon, and apparently has no deleterious effects on initial prognosis. A timely diagnosis requires an increased awareness to distinctive features.