Aim of Study: To assess knowledge, attitude and practice regarding geriatric depression among primary care physicians (PCPs) in Aseer Region. Methodology: Following a cross-sectional design, this study included 330 PCPs in Aseer Region, Saudi Arabia. A self-administered questionnaire was constructed by the researchers to assess participants' knowledge, attitudes and practices about geriatric depression. Results: Regarding geriatric depression, 30% of PCPs had poor knowledge. 94.2% had a positive attitude toward management of geriatric depression, while 27% had poor practices regarding management of geriatric depression. More than one third of participants (35.8%) do not use any standard test to screen for late life depression. Only 64.2% use clinical guidelines for the diagnosis and treatment of late life depression. while 10.6% of PCPs do not request any laboratory test to identify the cause for geriatric depression. The most frequently prescribed medications for depression among elderly patients were selective serotonin reuptake inhibitors (78.2%), while 48.8% of participants apply cognitive behavioral therapy to their geriatric depression patients. PCPs' knowledge grades differed significantly according to their age (p=0.019). PCPs with higher duration of experience had significantly higher percentage of good knowledge grades than those with less experience (28.1% and 17.1%, p<0.001). Those who attended psychiatry continuing medical education (CME) courses had significantly higher percentage of good knowledge grades than those who did not (27.1% and 17.5%, p=0.015). PCPs' attitude toward management of geriatric depression differed significantly according to dealing with depression cases (p=0.029), while their practice grades differed significantly according to their age (p<0.001) and duration of experience in primary health care (p=0.01). Those who attended psychiatry CME courses had significantly higher percentage of good practice than those who did not (51.9% and 45.8%. p=0.002). Participants' use of clinical guidelines for diagnosis and treatment of geriatric depression was significantly more by those who attended psychiatry courses (p<0.001) and also by those who dealt with cases of depression (p=0.008). Conclusions: PCPs knowledge regarding geriatric depression is suboptimal. Most PCPs have a positive attitude toward geriatric depression, but routine screening of elderly patients is mostly not fulfilled. PCPs' CME, experience and training are the main determinants for better knowledge, positive attitude and more practice regarding diagnosis and management of geriatric depression. Therefore, PCPs should be encouraged to attend CME on mental health of the elderly and to be trained on routine psychiatric screening of elderly and to use clinical guidelines for diagnosis and management of geriatric depression.