Observed level intervals within and between the configurations 2s² 2p³, 2s2p⁴ and 2p⁵ of the nitrogen sequence are compared with the corresponding theoretical values derived from the tables of Cheng, Kim and Desclaux. The differences are expressed by suitable functions of Z which give the systematic correction to the theoretical values and reveal the accidental errors in the experimental values. The technique is the same as was used in previous examinations of the Li, Be, B, O and F sequences. The results are summarized in tables of recommended level values (Z = 10-36) and recalculated wavelengths.