The color of urine is an important factor in urine examination, which can help physicians differentiate various diseases. Today, it is known that certain dyes, drug intoxications, and diseases can induce green urine discoloration. In the view of traditional Persian medicine, which is based on humoral medicine, green urine discoloration is generally referred to the dominance of coldness in the body. In fact, it is considered to be a result of a special kind of humoral imbalance and fluid depletion or retention in the human body. Persian scholars believed that green urine could be an indicator of intoxication or a predictor of an imminent spasm or convulsion in pediatric patients. Further investigations could result in finding new diagnostic scales of urine color based on the teachings of traditional Persian medicine.