Nephrolithiasis is a common, painful, costly and recurrent disease, the management of which remains to be an enigma. Phytotherapeutics could be useful as either alternative or complementary therapies in the management of nephrolithiasis. This study was designed to test the efficacy of Cymbopogon proximus (CP), a traditional Sudanese plant commonly known as "Mahareb", in preventing ethylene glycol-induced nephrolithiasis in rats. Thirty male Wistar albino rats were divided randomly into 3 groups of 10. Group 1 was the normal control. Group 2 (stone group) had free access to drinking water containing 0.75% ethylene glycol (EG) and 2% ammonium chloride (AC). Group 3 (test group) was treated as group 2 and was simultaneously injected with C. proximus 5% aqueous extract at a dose of 1.5 ml/100 g body weight/day for 10 days. At the end of the treatment period, serum levels of creatinine, blood urea nitrogen (BUN), calcium and phosphorous were determined; measurements of kidney calcium levels were also performed and kidney histopathological examinations were done. The stone group had the highest levels of serum calcium and BUN as well as the highest kidney calcium level. Large crystal deposits were also seen in this group. The CP treated group showed significantly lower levels of serum calcium, serum BUN and kidney calcium (p<0.01); crystal deposits were not observed in this group. The results obtained suggest that CP has a significant protective effect against ethylene glycol-induced nephrolithiasis in rats.