The purpose of this study was to explore O'Connor's four factors contributing to mothers' uncertainty concerning gastrostomy tube (G-tube) insertion in their children (lack of information; unclear value trade-offs; lack of support; social pressure) in a substitute decision-making context. Fifty mothers participated in one semi-structured interview at the time of their children's G-tube insertion. Children's ages ranged from 2 weeks to 17 years, slightly more than half were male, and most had a primary diagnosis related to a neurological (n=27) or cardiac (n=10) condition. Two-thirds of the mothers identified topics about which they wanted more information, the majority reported both gains and losses associated with their decision, three-quarters reported that they had received support during decision making, and half reported that they had felt pressure from family and health care professionals. Results indicate that mothers' decisions about G-tube insertion are complex and difficult. The existence and importance of O'Connor's factors in this context are confirmed by mothers' accounts. Because these factors are believed to be modifiable, health care professionals have the opportunity to potentially minimize the extent to which the factors contribute to decision uncertainly. It is recommended that health care professionals implement interventions focused on minimizing uncertainty.