Background: Prior studies reveal a lack of illness understanding and prognostic awareness among patients with hematological malignancies. We evaluated prognostic awareness and illness understanding among patients with acute leukemia and multiple myeloma (MM) and measured patient-hematologist discordance. Methods: We prospectively enrolled patients with acute leukemia and MM at Mount Sinai Hospital or Yale New Haven Hospital between August 2015 and February 2020. Patients were administered a survey assessing prognostic awareness, goals of care (GOC), and quality of life. Hematologists completed a similar survey for each patient. We assessed discordance across the cohort of patients and hematologists using the likelihood-ratio chi-square test and within patient-hematologist pairs using the kappa (κ) statistic. Results: We enrolled 185 patients (137 with leukemia and 48 with MM) and 29 hematologists. Among patients, 137 (74%) self-identified as White, 27 (15%) as Black, and 21 (11%) as Hispanic. Across the entire cohort, patients were significantly more optimistic about treatment goals compared with hematologists (p = 0.027). Within patient-hematologist pairs, hematologists were significantly more optimistic than patients with respect to line of treatment (κ = 0.03). For both leukemia and MM cohorts, patients were significantly more likely to respond "don't know" or deferring to a faith-based response with 88 (64%) and 34 (71%), respectively, compared with only 28 (20%) and 11 (23%) of hematologists, respectively. Conclusions: We observed significant discordance regarding prognosis and GOC among patients with hematological malignancies and their hematologists. These data support future interventions to improve prognostic understanding among this patient population to facilitate informed treatment choices.