Summary: This paper is concerned with a connection found between the occurrence of asthmatic attacks on the one hand and lunar phases on the other. From observations carried out during a period of one year at the Clinic for Pediatrics of the Medical University of Szeged, it appears that in the period from the first quarter to the last quarter, the occurrence of attacks was more frequent than during the second half of the synodic lunar month. A very strong peak of frequency has been observed in the days following the full Moon.