To investigate the differences in patient/caregiver characteristics, their treatment needs, and the attending physician's understanding of those treatment needs according to the duration after diagnosis of dementia with Lewy bodies (DLB). This was a post hoc analysis of a multicenter, cross-sectional, questionnaire survey study. A total of 263 patient-caregiver pairs were reclassified into two groups according to the median duration after diagnosis of DLB as follows: short (<24months; S-group) and long (≥24months; L-group) post-DLB diagnosis duration. Treatment need was defined as the symptom domain that caused the patient or caregiver the most distress. Concordance rates between patient-physician and caregiver-physician were calculated for physicians' understanding of treatment needs. In this analysis, 126 pairs (32 physicians) and 137 pairs (34 physicians) were classified as the S- and L-groups, respectively. Patient and caregiver characteristics were broadly similar between groups (mean age for patients 78.7±6.6 vs. 79.8±6.7, for caregivers 64.7±12.9 vs. 64.9±12.8; number of male/female for patients 61/65 vs. 67/70, for caregivers 34/92 vs. 38/99), but the prevalence of parkinsonism (82.5% vs. 66.7%) and autonomic dysfunction (49.6% vs. 33.3%), severity of parkinsonism (MDS-UPDRS Part III total scores, 29.2±22.6 vs. 18.0±16.4; Part II total score, 14.6±12.0 vs. 7.6±7.9), and caregiver burden (J-ZBI_8 score, 9.1±6.7 vs. 7.5±5.8) were higher in the L-group than the S-group. Regarding treatment needs, the invalid answer rates for patients were 34.9% and 46.8%, and those for caregivers were 28.6% and 34.9% in the S- and L groups, respectively. Patients' treatment needs did not significantly differ (p=0.056), but S-group patients were more likely to select cognitive impairment (p=0.045) as their treatment need, whereas L-group patients were more likely to select parkinsonism (p=0.003). Caregivers' treatment needs significantly differed (p=0.032) between groups. S-group caregivers were more likely to select cognitive impairment (p=0.001), whereas L-group caregivers were more likely to select other symptom domains such as parkinsonism (S-group vs. L-group: 10.3% vs. 16.7%), psychiatric symptoms (20.6% vs. 24.6%), sleep-related disorder (4.0% vs. 7.1%), and autonomic dysfunction (4.8% vs. 9.5%). Concordance rates between patient-physician and caregiver-physician were low in both groups. There were some differences in characteristics according to the duration after diagnosis of DLB. Cognitive dysfunction may be a particular concern for patients and caregivers soon after diagnosis of DLB. Treatment needs of patients and caregivers for parkinsonism, psychiatric symptoms, sleep-related disorder, or autonomic dysfunction were different according to the duration after diagnosis of DLB. Physicians' perception of patients'/caregivers' treatment needs was poor regardless of the duration after diagnosis of DLB. UMIN Clinical Trials Registry (UMIN000041844).