Patients with refractory hematologic malignancies including those who develop recurrent disease after allogeneic hematopoietic stem cell transplantation (HSCT) have a dismal prognosis. Historically, both regimen-related mortality and disease recurrence have been significant causes of treatment failure in this heavily pre-treated patient population. The investigators institution has utilized mismatched family member donors for these patients for several reasons: (1) Only 30% of patients have matched related donors available; (2) transplantation can be performed more rapidly since the time to unrelated donor trans-plantation averages 3 to 4 months; (3) the alloimmune reactivity of natural killer (NK) cells following haploidentical HSCT has been shown to reduce relapse rates in certain patient groups; and, (4) no other curative treatment options are available.