<b><i>Introduction:</i></b> Although frequently assumed to be age-related changes, vascular white matter lesions (WML) are sometimes found in young adults. Etiology is usually attributed to sporadic small vessel disease; nevertheless, genetic disorders may also be implicated. We aimed to characterize the population of young adults with vascular WML in Neurology outpatient clinics. <b><i>Methods:</i></b> Neurologists from 12 Portuguese hospitals were invited to include patients aged 18–55 years evaluated in consultation, with vascular WML on MRI, scoring II or III in the Fazekas scale. Central imaging validation was performed by 2 independent, blinded, Neuroradiologists. Demographic and clinical data were collected as well as results of investigations performed. <b><i>Results:</i></b> During 2 years, 77 patients were included (mean age 47.7 years). Vascular risk factors were present in 88.3% patients (hypertension in 53.2%) and previous history of stroke in 36.4%. Patients without history of stroke were younger (46.6 ± 7.2 vs. 49.6 ± 3.9 years, <i>p</i> = 0.045) and had fewer vascular risk factors (<i>p</i> &#x3c; 0.001). They were more frequently females (87.8 vs. 46.4%, <i>p</i> &#x3c; 0.001), and headache (30.6 vs. 3.6%, <i>p</i> = 0.007), contrary to focal symptoms (16.3 vs. 53.6%, <i>p</i> = 0.001), was the most frequent reason of referral. Etiological investigations performed differed between Neurologists. A genetic disorder was identified in 6 out of 58 patients (CADASIL <i>n</i> = 5; COL4A1 <i>n</i> = 1). <b><i>Conclusion:</i></b> Young adults with vascular WML evaluated in Neurology outpatient clinics concentrate in the oldest age groups. Vascular risk factors should be screened carefully in this population. Among patients without history of stroke, females largely outweigh males. Diagnostic investigations performed do not follow a standardized protocol.