目的　探讨钩端螺旋体 Ｌ型感染与钩体脑动脉炎发病的可能关系。方法　对７４ 例钩体脑动脉炎患者血液及脑脊液进行钩端螺旋体普通培养、 Ｌ 型培养， 患者血清做显微镜凝集试验， 用免疫荧光染色确定钩体 Ｌ 型及其原菌型。结果　钩体脑动脉炎患者钩体 Ｌ型培养、普通培养、钩体 Ｍ Ａ Ｔ的阳性率分别为： ４７３ ％ 、１８９ ％ 、７０３ ％ 。分离出的钩体 Ｌ 型呈多形性。结论　钩端螺旋体 Ｌ 型感染与钩体脑动脉炎的发病关系密切。 Objective To investigate the possible relationship between leptospiral L-infection and the incidence of leptospirosis. Methods Seventy - four patients with leptospheric cerebral arteritis were routinely cultured in serum and cerebrospinal fluid (CSF), cultured in L - form and the serum of patients were examined by microscope. The L - form and its prototrophs were identified by immunofluorescence staining. Results The positive rates of L-shaped culture and common culture of L-shaped hooks with L-ascites were 473%, 189% and 703% respectively. Isolated L-shaped hook was pleomorphic. Conclusion Leptospira L infection is closely related to the incidence of leptospirosis.