The absorption due to the ν3 band of methane in solar spectra has been used to deduce the methane content of the lower stratosphere. The spectra were taken from an aircraft flying at altitudes between 10 and 18 km and at latitudes from 18 °N to 66 °N. It is concluded that methane is uniformly mixed up to 25 km with an average mixing ratio of 0.94 ± 0.16 p.p.m.v. No large latitudinal variation of the mixing ratio was observed.