Pain and discomfort during breast examination can affect a woman's adherence to breast cancer–screening programs. The aim of this study was to determine whether a nursing intervention protocol that provides verbal information and support to women could reduce pain during mammography. A randomized controlled trial of 436 Spanish women aged 50–69 who attended a breast-screening program was performed. The experimental group received a customized nursing intervention that provided face-to-face information and emotional support during the examination. Pain and anxiety were measured using a visual analogue scale and the State-Trait Anxiety Inventory, respectively. Data regarding several potential confounders were also collected. The adjusted means of pain level in the study group were obtained from multiple linear regressions, and the adjusted odds ratios (OR) and 95% confidence intervals (CI) were obtained via logistic regression. After the intervention, the level of pain was significantly lower (p= .03) in the experimental group (0.98 ± 2.28) compared with the group treated with normal care (1.48 ± 2.29). Consequently, the probability of feeling pain during mammography was lower among women in the experimental group (OR = 0.44; 95% CI: 0.24–0.81). The intervention was more effective among women with the highest anxiety levels (OR = 0.33; 95% CI: 0.11–0.98), who did not expect pain (OR = 0.28; 95% CI: 0.08–0.97), and who did not fear the outcome of the mammography (OR = 0.18; 95% CI: 0.04–0.85). Providing verbal information, as well as supporting the women during the test, is a simple and achievable intervention for nurses and can help to reduce pain during screening mammography.