Five cases of ataxia-telangiectasia are reported. In 4 cases, there is no parental consanguinity. In the other case the parents are unknown. The maternal grandfather of one of the patients hadtelangiectasiae in the scalp, face and ears, but no ataxia and the γA-globulin content in the serum was normal. There was no known case of ataxia in any of the families. All of the patients had had bronchitis, but only 3 of them had been particularly susceptible to respiratory infections. The growth was retarded in all. None of them presented deformities of the feet or kyphoscoliosis.

Only in one patient was the motor development retarded during the first year of life, in the remaining the disturbance of the psychomotor development appeared in the form of ataxia in the course of the second or third year of life when the patients started to walk.

One patient developed telangiectasiae at 2-3 years of age, the others a t 5-7 years of age. Patches of poor pigmentation of the skin in the fa03 were present in 4 patients. Choreoathetotic movements and a tendency to turn the eyes upwards when focusing was observed in 4 cases.

The sensibility was normal in all cases. The deep reflexes were normal in one case and impaired in four. In the latter normal reflexes had been demonstrated at an earlier age. Intelligence fell within the lower limits of normality in all patients. No definite progressive impairment was demonstrable.

The EEG was normal in 2 cases. In one patient a moderate general cerebral dysrhythmia was found, most marked over the right temporal region but no epileptogenic activity. I n another a focus was registered in the left temporal region. One patient had not been submitted to EEG.

Paper chromatography of the urine revealed a normal amino acid pattern in 4 cases, the 5th was not examined.