Vitamin A prophylaxis is an essential public health intervention to prevent childhood blindness, reduce morbidity, and enhance the immune system of children under five years of age. Lack of awareness among mothers regarding the importance and schedule of Vitamin A supplementation can result in poor health outcomes.

Objectives: To assess the knowledge of Vitamin A prophylaxis among mothers of under 5 years age children; to evaluate the effectiveness of structured teaching program on their knowledge; and to find the association between knowledge level and selected demographic variables.

Methods: A quantitative research approach and pre-experimental one group pre-test post-test design was adopted. The study was conducted at Behta, Lucknow among 30 mothers of under-5 children selected through non-probability convenient sampling technique. Data were collected using a self-structured knowledge questionnaire.

Results: The study revealed that in the pre-test, 30% of mothers had inadequate knowledge and 70% had moderate knowledge. After the intervention, in the post-test, 53.3% of mothers had adequate knowledge, and 43.3% had moderate knowledge, while none remained with inadequate knowledge. Pre intervention mean knowledge score was 10.4±2.97321after intervention it was found to be 15.43±5.0244 a change of 5.03 in knowledge score was observed which was found to be statistically significant. The calculated “t” value is = 9.109 is more than table value 2.05 is highly significant at 0.05 level. The improvement in knowledge was found to be statistically significant.

Conclusion: The study concluded that the structured teaching program was effective in improving knowledge regarding Vitamin A prophylaxis among mothers of under 5-year-old children.