Purple urine bag syndrome is a rare condition that occurs predominantly in the elderly, immobilized and bearer of chronic bladder catheter. It is a phenomenon usually associated with urinary tract infection, particularly in the presence of high bacterial load. The presence of alkaline urine, constipation, high-protein diet and dehydration are predisposing factors. In most cases it is an asymptomatic condition. We described the case of an elderly patient admitted to the geriatric Department in which purple urine was found in the urine collection bag. The culture of urine showed the presence of infection with Klebsiella pneumoniae. Targeted antibiotic treatment and proper hydration determined the resolution of the phenomenon and the resolution of the infection. Although it is an alarming phenomenon due to the particularity of the color of the urine, it is a treatable and solvable condition with an adequate specific antibiotic treatment. Prevention measures are equally effective and consist in eliminating the risk factors for this condition.