This study is aimed to compare the effect of two methods of short messages and group training on level of knowledge and practice of middle-aged women about breast cancer screening procedures. This clinical trial study was done on 210 women aged 40-60 years in Mahshahr city, Iran. Eligible middle-aged women were randomly assigned in two groups of short message (n = 105) and group training (n = 105). Data collected through a questionnaire which included three parts (demographic, knowledge and practice of women about breast cancer and screening procedures). Group training was educated for two sessions in 2 weeks that each session lasted 2 h. In the short message group, every woman received texts about breast cancer, reasons, and preventive methods, three times a week, for 2 weeks. The questionnaire (knowledge and practice) was completed 2 months after educational intervention. Data was analyzed using independent t test, paired t test, and chi-square. Results of this study showed that average score of knowledge in two groups increased significantly, from 34.4 ± 7.54 to 40. 8 ± 7.18 in the short text messages (SMS) and from 35 to 39.75 in the group training (P > 0.05). Also, the score of breast examination by health provider in the SMS group was significantly higher than that in the group training, but the score of breast self-examination in the group training was higher than that in the short message (P < 0.05). The results showed that training by each way is effective to increase knowledge and performance of women about breast cancer screening methods. Further studies to compare the cost-effectiveness of two methods are recommended.