Objectives: To ascertain the prevalence of cognitive impairment in the low income, urban geriatric population, and, to assess the prevalence of treatable mental health problems that could contribute to cognitive impairment. Methods: Geriatric patients (age 65+, N=79) were recruited when they presented for scheduled medical care at an academic primary care clinic in a low-income neighborhood of Philadelphia, Pennsylvania. Participants answered questions regarding their demography, psychiatric history, and substance use history. The General Practitioner Assessment of Cognition (GPCOG) was used as the screening instrument, and the following standardized tools were also administered: Geriatric Depression Scale (GDS-5), Geriatric Anxiety Inventory (GAI-SF), and the Charlson Comorbidity Index. A urine specimen was tested for drugs of abuse. Results: Based on the GPCOG screen, the prevalence of cognitive impairment was 78%. Severe cognitive impairment, consistent with a diagnosis of dementia, was observed in 19% of the study population. All subjects with positive urine drug screens were in the impaired group and most drugs detected were prescribed by physicians. Conclusions: The majority of elderly patients receiving primary care in a low-income urban setting have some degree of cognitive impairment, some consistent with frank dementia. All subjects with a positive urine drug screen were cognitively impaired. Detecting cognitive impairment should prompt consideration of the effects of prescribed medication on cognition. In addition substance use disorders should be considered. Screening for cognitive impairment in older adults can detect reversible causes of impairment and prompt discussion about the effects of medication and substance use on cognition.