Aim Neurological symptom severity is a prognostic factor for post‐stroke activities of daily living (ADL). Recently, it has been reported that white matter lesions indicate poor functional prognosis in patients with stroke. The present study investigated the influence of white matter lesions on the ADL of older patients with stroke who have mild neurological symptoms. Method We investigated ADL at discharge in 44 patients with stroke (men, n = 27; women, n = 17; mean age 78 years [range 71–85 years]) aged ≥65 years with National Institutes of Health Stroke Scale scores of ≤5 (cerebral infarction, n = 37; cerebral hemorrhage, n = 7). We used single correlation analysis and multiple regression analysis to investigate factors that correlated with ADL at discharge. ADL at discharge was also evaluated on the basis of white matter lesion severity (Fazekas classification, grades 0–3). Results Single correlation analysis showed that age (r = −0.36, P = 0.016), male sex (r = 0.362, P = 0.016), neurological symptom severity (r = −0.361, P = 0.016), ADL on starting rehabilitation (r = 0.685, P < 0.001) and white matter lesion severity (r = −0.361, P = 0.016) significantly correlated with ADL at discharge. Multiple regression analysis showed that ADL on starting rehabilitation (β = 0.519, t = 4.723, P < 0.001) and white matter lesion severity (β = −0.309, t = −3.057, P < 0.01) were statistically significant prognostic factors for ADL at discharge. ADL at discharge score was significantly lower in the group with high white matter lesion severity (Fazekas, grade 2) than in the other two groups (Fazekas, grade 0, P < 0.01; Fazekas, grade 1, P < 0.05). Conclusion Severe white matter lesions are a prognostic factor for poor ADL at discharge in older patients with stroke who have mild neurological symptoms. Geriatr Gerontol Int 2016; 16: 942–947.