We have developed a systematic study for the investigation of resonance structures of the substituted BODIPYs. Aromaticity of two rings of BODIPY were calculated by means of NICS (Nucleus independent chemical shift) values and these values gave us an insight to predict dominant resonance structure between two different resonance forms of BODIPYs. Furthermore, bond order comparisons were utilized to specify dominant forms of the resonance structures. BODIPYs substituted with electron donating (EDG) or withdrawing groups (EWG) at different positions were analyzed and it was observed that character of substituents affected the aromaticity as well as dominant resonance structure. Substituent positions were also investigated and some important points were yielded from these calculations. We further extended the study to aromaticity of pyridine or benzene[b]-fused BODIPYs. (C) 2015 Elsevier B.V. All rights reserved.