Randomized comparison of ceftriaxone and cefotaxime in Lyme neuroborreliosis. In this prospective, randomized, open trial, 33 patients with Lyme neuroborreliosis were assigned to a 10-day treatment with either ceftriaxone, 2 g intravenously (iv) every 24 h (n = 17), or cefotaxime, 2 g iv every 8 h (n = 16). Of the 33 patients, 30 were eligible for analysis of therapeutic efficacy. Neurologic symptoms improved or even subsided in 14 patients of the cefotaxime group and in 12 patients of the ceftriaxone group during the treatment period. At follow-up examinations after a mean of 8.1 months, 17 of 27 patients examined were clinically asymptomatic. In one patient Borrelia burgdorferi was isolated from the cerebrospinal fluid (CSF) 7.5 months after ceftriaxone therapy. CSF antibiotic concentrations were above the MIC 90 level for B. burgdorferi in nearly all patients examined. Patients with Lyme neuroborreliosis may benefit from a 10-day treatment with ceftriaxone or cefotaxime. However, as 10 patients were symptomatic at follow-up and borreliae persisted in the CSF of one patient, a prolongation of therapy may be necessary. 