AimThe aim of this study was to determine the effect of back and breast massage on the amount of milk production and level of anxiety in mothers with preterm birth. MethodThe study was carried out with 36 mothers who had preterm delivery June 2021–May 2022 in a Maternity Hospital in Türkiye. ResultsNo difference was found between groups amount of breast-milk in first and second day. However, compared to the control group, the amount of breast-milk was found to be significantly higher in the group that received back and breast massage (p < 0.05) in the third, fourth, fifth, sixth and seventh day. The state of anxiety scores of the mothers in experimental groups at sixth week were found to be significantly lower than control group (p < 0.01). ConclusionThe amount of expressed breast-milk with back and breast massage was higher than the mothers in the control group and their state anxiety scores were lower.