Background and Objective: Infancy period has an essential role in future health of individuals due to development of human body structure over this period of life. Sufficient nutrition and correct nutritional patterns have great impact on infancy health. The objective of this study was to determine the effect of training on awareness, attitude and practice of mothers who had infants. Materials and methods: This study was a quasi experimental (before and after the intervention) study without a control group. Study sample included 110 mothers referring to health houses of Abhar city who had at least one infant under 1 year old. Before the intervention, knowledge, attitude and practice of mothers concerning complementary feeding were evaluated using a standard questionnaire. Validity and reliability of the questionnaire was tested. Intervention program included training sessions with group discussions and role playing, and social worker as facilitator of the group. Training sessions were held twice a week for 6 weeks. One month after the intervention, knowledge, attitude and practice of mothers were measured. Results: Scores of knowledge and attitude showed a significant improvement after the intervention as compared to before the intervention (p<0.001). In practice domain, mothers had significant changes in choosing of type of complementary feeding, sufficient number of feeding their infants during the day, and proper storage of complementary food after training (p<0.001). Conclusion: Training in supplementary nutrition by health workers through group discussion and role play has an important effect in improving knowledge, attitude and practice of mothers. Referencs 1- Imdad M, Yakoob MY, Bhutta ZA. Impact of maternal education about complementary feeding and provision of complementary foods on child growth in developing countries. BMC Public Health. 2011 11: S25. 2- Kolahdooz F, Najafi F. 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