The aim of this study was to compare microleakage of resin-based sealant Helioseal F with or without bonding agent. Fifty-six sound human maxillary first premolar teeth were collected which were extracted for orthodontic purpose, then the teeth were randomly divided into two main equal groups; group (1) and group (2), the first group was treated with Tetric N Bond bonding agent, whiles the second group without.