The measurement of the phase fluctuations caused by spontaneous emission in the oscillation of a He&sngbnd;Ne laser operating at 1.15 &mgr; is reported. The frequency fluctuations in the signal resulting from heterodyning two independent modes in the laser were measured asf2(&ngr;) =(9.6±2)×10−2Hz2/Hz for 1.65×107stored photons per mode andf2(&ngr;) =(2.7±0.3)×10−1Hz2/Hz for 6.2×106stored photons per mode. These values are to be compared with the theoretical minima for these cases, which are calculated to bef2(&ngr;) =5.1×10−2Hz2/Hz andf2(&ngr;) =1.4×10−1Hz2/Hz, respectively.