Acute focal bacterial nephritis (AFBN) is a rare pre-suppurative complication of acute pyelonephritis that can be severe, particularly in elderly patients.Describe the epidemio-clinical, microbiological, radiological, therapeutic characteristics and outcomes of AFBN.We conducted a cross-sectional study including elderly patients who were hospitalized in our department for AFBN between 2014 and 2024.Twelve patients were included, eight women (75%) and four men (25%), with a mean age of 67 years (range 65–80 years). The most common comorbidity was diabetes mellitus (58.3%). Clinical manifestations were dominated by fever (83.3%), flank pain (66.7%), and dysuria (50%). Leukocytosis and a C-reactive protein level > 200 mg/L were noted in 83.3% and 66.7% of cases respectively. Escherichia coli was the most frequently isolated pathogen (58.3%). Radiological assessment was primarily based on CT urography (66.7%) and renal ultrasonography (33.3%). Focal bacterial nephritis was multiple in three cases (25%).  All patients were treated with dual antibiotic therapy: a combination of a third-generation cephalosporin and an aminoglycoside in nine cases (75%) and a combination of a third-generation cephalosporin and a fluoroquinolone in three cases (25%). The clinical and radiological course was favorable in all patients (100%) after a mean duration of antibiotic therapy of 19.1 days (14–21 days).AFBN in the elderly is likely underdiagnosed, as its clinical presentation closely mimics that of uncomplicated acute pyelonephritis based on clinical features alone. AFBN in the elderly occurs more frequently in women with diabetes mellitus being the most common associated comorbidity. Escherichia coli remains the predominant pathogen. Diagnosis relies on radiologic imaging. The uniformly favorable outcomes observed with prompt dual antibiotic therapy underscore the importance of early recognition.AFBN requires early diagnosis and prompt appropriate management, with heightened vigilance in elderly patients to preserve renal function.