Vitamin A deficiency remains a major cause of preventable childhood blindness and of infection-related illness and death in children under five years, and the knowledge of mothers is central to its prevention. Despite more than three decades of a national prophylaxis programme in India, deficiency persists among poor and underprivileged populations.

To assess the pre-test and post-test knowledge of mothers of under-five children regarding vitamin A deficiency and its prevention, to determine the effectiveness of an information booklet, and to find the association between knowledge and selected socio-demographic variables.

A quantitative, pre-experimental, one-group pretest–posttest study was conducted in selected slum areas of Rewa, Madhya Pradesh, in April 2023. Fifty mothers of under-five children were recruited by non-probability convenience sampling. Data were collected with a self-structured questionnaire on eight socio-demographic characteristics and a 30-item multiple-choice knowledge questionnaire (maximum score 30; poor 0–10, average 11–20, good 21–30). An information booklet was given after the pre-test, and the post-test was administered on the seventh day with the same tool. Data were analysed with frequencies, percentages, means, standard deviations, the paired t-test and the chi-square test.

Before the booklet, 64.0% (n = 32) of mothers had poor knowledge, 28.0% (n = 14) average and 8.0% (n = 4) good knowledge. After the booklet, no mother had poor knowledge, 20.0% (n = 10) had average and 80.0% (n = 40) had good knowledge. The mean knowledge score increased from 12.52 ± 3.23 to 24.75 ± 2.33 (mean gain 12.23; paired t = 3.77, df = 49, p < 0.001). Pre-test knowledge was significantly associated with the number of under-five children, educational status and source of health information, but not with age, family income, occupation, type of family or housing condition.

Baseline knowledge of vitamin A deficiency and its prevention was poor among mothers in the study area. An information booklet was followed by a significant improvement in knowledge. Validated, illustrated written material may be a practical way of educating mothers in slum communities; because the design lacked a control group and followed mothers for only seven days, the findings should be confirmed in controlled studies with longer follow-up.