A residential metal roof will not increase the likelihood of lightning striking a home. However, if a home were hit by lightning, the metal roof would disperse the energy safely throughout the structure. Since metal roofing isn’t combustible or flammable, it’s a low risk and desirable roofing option where severe weather is concerned, especially for lightning.

More Myth-Busters: http://www.metalroofing.com/v2/content/guide/newsletters/04-0701.cfm