Objective Although cancer patients frequently experience self‐perceived burden to others, this perception has not been enough studied. The aim of this study was to investigate the prevalence of self‐perceived burden to the primary caregiver (SPB‐PC) and associated factors in an older patient population with hematologic malignancies at the time of chemotherapy initiation. Methods In total, 166 consecutive patients with hematologic malignancies aged ≥65 years were recruited at the time of chemotherapy initiation. Patients' SPB‐PC was assessed using a 100‐mm visual analogue scale (VAS). Characteristics potentially associated with SPB‐PC, including sociodemographic and medical characteristics, physical functioning status (Karnofsky performance score, activities of daily living (ADL)/instrumental ADL), symptoms (fatigue, pain, nausea, quality of life), psychological distress (Hospital Anxiety and Depression Scale (HADS)), perceived cognitive function (Functional Assessment of Cancer Therapy Cognitive (FACT‐Cog) Scale), and patients'/primary caregivers' personal relationship characteristics (family tie, support), were assessed. Results Thirty‐five percent of patients reported moderate to severe SPB‐PC (VAS ≥ 50 mm). Patients' SPB‐PC was associated with lower Karnofsky performance (β = −0.135, p = 0.058) and ADL (β = −0.148, p = 0.037) scores, and higher HADS (β = 0.283, p < 0.001) and FACT‐Cog perceived cognitive impairments subscale (β = 0.211, p = 0.004) scores. The proportion of explained variance was 23.5%. Conclusions Health care professionals should be aware that about one third of older cancer patients experience moderate to severe SPB‐PC at the time of chemotherapy initiation. They should adapt their support of patients who report such a feeling. Copyright © 2016 John Wiley & Sons, Ltd.