Several published papers identified microstructural banding as a factor in susceptibility to hydrogen induced cracking (HIC). In the present study over 50 plates from more than 15 heats of A516-70 steel were analyzed for microstructural characteristics including banding index per ASTM E1268 for chemical composition for HIC behavior per NACE TM0284 and for cleanliness rating per ASTM E45. The correlation between HIC behavior and banding index was weak. Scanning Electron Microscopy analyses of opened HIC cracks was used to identify HIC initiation sites. Non-metallic inclusions and untempered martensite were identified as the sources of high CLR values in HIC tested samples. These microstructural characteristics rather than the banding index per se are significant causes of HIC in pressure vessel steels