Studies using a model of non-infectious diarrhea, have shown that increasing fecal mass by using laxatives resulted in greater fecal losses of nutrients and lower intestinal absorption. In the present study we used a diuretic to determine if increasing urine volume could result in greater urinary losses of essential nutrients. This is a relevant question because diuretics are widely and successfully used in the treatment of diseases associated with water retention and hypertension. They are known to increase potassium losses. However, there is less information on the effect of diuretics on the urinary losses of essential nutrients. Accordingly, urinary nitrogen, phosphorous, sodium, potassium, magnesium, zinc and retinol were measured in young rats consuming increasing concentrations of furosemide (0, 0.5, 1.0, 1.5 mg/g diet) in the diet over 15 days. The results showed that dietary furosemide caused a dose-dependent polyuria. In addition it reduced food intake and feed efficiency and leaded to poor growth and greater urinary losses of all the measured nutrients and electrolytes. These losses were proportional to urine volume and represented an important fraction of the rats daily intake. The losses were negatively associated with the body and liver content of the same electrolytes and nutrients. In general, this study showed that the diuretic furosemide caused malnutrition in a short period of time by reducing food intake as well as the capacity of retaining macro and micronutrients including the liposoluble vitamin A in a relatively short period of time. This study, together with our previous studies on diarrhea, indicate that proper nutrient utilization requires both an adequate intestinal and renal function.