The diode laser absorption spectrum of the ν19a band of aniline cooled in a supersonic expansion has been recorded and transitions with low J, Ka and Kc values (2–28) are reported. The band center has been found at ν̄0=1504.297cm−1 and rotational constants for the upper state have been determined from a least-squares fitting to the experimental data. The effect of the centrifugal distortion has also been studied, and approximate values of quartic constants are provided. In addition, the possible effect of the inversion mode of the NH2 group on the ν19a mode is analyzed.