Purpose: This study was done to test the effects of Oketani breast massage on breast pain and breast milk pH of mothers, and sucking speed of neonates. Methods: A nonequivalent control group and a pretest-posttest design was used. Postpartum mothers complaining of breast pain were recruited at a postpartum care center. The application of Oketani breast massage by an Oketani massage therapist was the experimental treatment. The control group received the conventional massage technique from a nurse at the postpartum care centre. The collected data were analysed using a $x^2$-test and a t-test with the SPSS WIN 12.0 program. Results: The participants were homogeneous in age, gestation period, and birth weight. Breast pain (t=8.384, p<.001) was significantly relieved, and breast milk pH (t=4.793, p<.001) was significantly increased in the experimental group compared to the control group. The sucking speed of the neonates in the experimental group was significantly increased compared to the control group (t=9.920, p<.001). Conclusion: These findings indicate that Oketani breast massage is effective in relieving breast pain and increasing breast milk pH as well as the sucking speed of neonates.