Over 80 million MRI procedures are now performed each year worldwide. Magnetic resonance imaging (MRI) is a frequently used imaging technique not only for diagnostic purposes but also in research settings. Adolescent girls report a greater number of worries, more separation anxiety, and higher levels of generalized anxiety. Claustrophobia is common during MR scanning because of the enclosed nature of cylindrical whole-body MR scanners. This study aimed to investigate the effect of health instructions on anxiety levels and claustrophobia among female adolescents undergoing Magnetic Resonance Imaging. A quasi- experimental research design was used. This study was conducted at waiting area of El Menofia University Hospital. Four tools were used to collect data; Socio-Demographic characteristic of Female Adolescents structure questioner sheet to assess knowledge related to claustrophobia Assessment sheet, and State–Trait Anxiety Inventory sheet. The majority of female adolescent had unsatisfactory knowledge in pretest regarding preparation before MRI exam as compared to post test. There was highly statistically significant difference among levels of anxiety from pre test and post test. Conclusion; Female adolescent who are undergoing magnetic resonance imaging examination cannot terminate the procedure due to producing anxiety and claustrophobia, so health instructions for those is very necessary, which has an effect on reducing anxiety level and claustrophobia related to magnetic resonance imaging examination. Recommendations; The researchers suggested conduction of a designed program for patients who cannot terminate the procedure successfully and reappointed for another examination, Patient meeting with psychologist before MRI, Establishing enjoyable posters and pamphlets into the MRI waiting room, Teach the female adolescents' methods of coping therapeutically with claustrophobia and anxiety, Presences of relative with female adolescents during preparation for MRI