Background: Hearing loss is a worldwide public health issue that requires more attention from health care personal. So primary health care nurses have the main role in early detection of newborn hearing loss. Purpose: This study was conducted to assess effect of training intervention on enhancing knowledge and practice of primary health care nurses regarding newborn hearing screening.  Design: A quasi-experimental research approach was used (pre and post-test). Setting: This research was carried out at five primary health care units affiliated to Ministry of health at kom Hamada center in El Behera Governorate. Sample: This study was conducted on 116 primary health care nurses. Instruments: a- Self-administered structured questionnaire included personal characteristics, nurses' knowledge about newborn hearing loss and hearing screening test b- Observational checklist for nurses, practices related to hearing screening for newborns was used. Results: The main findings revealed that nurses who had good knowledge increased from 23.3% on pre-test to 86.2 % on posttest. While in the retention test, 87.1% of them had good knowledge. Also, the findings revealed that on post and retention test showed a highly significant improvement in hearing screening practice than in pre-test. In addition, there were a highly statistical significant improvement in both knowledge and practice among studied nurses.  Conclusion: It was concluded that there training intervention was effective in improving nurses' knowledge and practice regarding newborn hearing screening on posttest and retention tests than pretest. Recommendations: Continuous training and teaching sessions to enhance knowledge and practice of nurses on hearing screening test should be applied in all primary health care units.