This study is a phase I, open-label, single-arm, dose escalation trial to determine the safety and activity of lenalidomide combined with lintuzumab in patients with MDS. Small groups of 3-6 patients will be treated with pre-specified doses of lenalidomide and lintuzumab and will receive 3-week cycles of combination therapy.

Inclusion Criteria:

1. Disease confirmation of MDS.
2. Between 5% and 30% blasts in the bone marrow.
3. Received treatment for cytopenias within 2-months
4. ECOG ≤ 2.

Exclusion Criteria:

1. Received prior therapy with lenalidomide, gemtuzumab ozogamicin (Mylotarg®).
2. Received chemotherapy/radiotherapy within 4 weeks of study registration.
3. Received prior bone marrow transplant.
4. 5q- chromosomal deletion in malignant cells.