Infrared thermography was used to monitor the healing process at flipper tag sites in gray seal (Halichoerus grypus) pups. We tested the hypothesis that tagging would result in a rise in surface temperature associated with tag site healing processes compared with adjacent untagged areas of the flipper. Prior to tagging thermal images were recorded of the dorsal side of hind flippers of pups tagged in early lactation (n= 20) and at weaning (n= 19) on the Isle of May, Scotland (56°11′N, 02°33′W) from October to December 2008. Pups tagged in early lactation were sampled again at late lactation, at weaning and then every 3 d for an average of 29 d post-tagging while pups tagged at weaning were sampled every 3 d for an average of 17 d post-tagging. Tag sites were also scored for signs of infection or swelling at each sampling. Results showed that (1) small temperature increases associated with wound healing processes around the tag site returned to pre-tagging levels before animals leave the island and (2) there was little evidence of tagging-related infections or tag loss irrespective of age at tagging.