SUMMARY This appears to be the first report of meningitis due to Pseudomonas paucimobilis and the first report of a clinically significant isolate of this species in the UK. Characteristics by which the species may be recognised are given, and attention is drawn to the possible confusion of Ps. paucimobilis with other yellow-pigmented pseudomonads and Flavobacterium species.Pseudomonas paucimobilis is a species described only recently (Holmes et al., 1977). The strains on which the description of the species was based had been recovered largely from human clinical specimens and the hospital environment, but none was known to be the causative agent of infection. Although the clinical significance of Ps. paucimobilis remained unknown we now report what is, as far as we know, the first case of meningitis due to this species. Case reportA 39-year-old male epileptic was admitted on 24 June 1978. He had had epilepsy for three years and was currently treated with phenobarbitone 60 mg and phenytoin 100 mg three times a day. He complained of headache for two days and had started to have convulsions on the day of admission. This was controlled with a single dose of 20 g diazepam intravenously. However, he remained very drowsy 6 hours later, and the axillary temperature was found to be . Clinical examination showed neck stiffness and a positive Kernig's sign.A lumbar puncture was performed and turbid fluid obtained, giving the following results: white cells 0-2 x 109/1 (200/mm3), 95 % lymphocytes, 5 % neutrophils; protein 0 4 g/l (40 mg/100 ml), glucose 3-7 mmol/l (67-2 mg/100 ml); the blood glucose level was 4-7 mmol/l (85 mg/100 ml). Gram and ZiehlNeelsen films were initially reported as negative.