Needle-related procedures are reported to be problematic for children. In a school-based celiac disease screening, 12-year-olds’ experiences with relaxation and guided imagery (R-GI) during venipuncture were investigated. One group tried nurse-led R-GI (n = 60) and another group received standard care (SC; n = 49). A mixed method design was applied using short written narratives, facial affective scale (FAS), and visual analog scale (VAS) for pain intensity. Qualitative content analysis highlighted that diversity and contradictions when facing blood tests. FAS scores were significantly lower in the SC group before (p = 0.01), during (p = 0.01), and after (p = 0.01) venipuncture. VAS scores did not differ between the groups. The blood test was mostly experienced as unproblematic, and GI during venipuncture did not decrease pain or affect. However, the fact that a number of children scored high FAS indicates a need for effective methods to help children cope with needle-related school-based procedures.