Phase shifting of the circadian conidiation rhythmof Neurospora crassaby pulse treatments with different temperatures, which ranged from 10° to 35°, was compared for the wild type and the clock mutant,frq‐7,in liquid culture. Both strains showed similar phase response curves’ for high temperature (35°) but different phase response curves for low temperature (15°). In the wild type strain, pulses with temperatures higher than 25° caused small shifts in phase in the subjective day phase but pulses with temperatures lower than 25° caused large phase‐delay in the same phase. The clock mutant, frq‐7, showed similar responses to temperature pulses in phases other than the late subjective day phase (CT 9 to CT 14), during whichfrq‐7was almost intensitive to pulses with temperatures lower than 25°. This phase (CT 9 to CT 14) coincided with the phase which has previously been proposed to be affected by mutations at thefrqlocus.