Background: A pre-lacteal feed is any food other than mother's milk provided to a new-born before breastfeeding begins. It has an effect on the timing of breastfeeding initiation and exclusive breastfeeding activities. Pre-lacteal feeding decreases the immunological benefits derived from colostrum while also increasing the risk of infection. Pre-lacteal feeding is a dangerous infant feeding technique that is commonly used in the developing world, including Bangladesh. The present study might help us to become well aware of the correct weaning practices by the rural mothers, their beliefs and their customs and thus may guide us regarding the ways to improve the nutritional status of the rural children as well as to improve the knowledge and practice regarding pre-lacteal feeding and weaning of the mothers. Materials and Methods: This was a cross-sectional type of descriptive study carried out with a view to assess knowledge and practice about pre-lacteal feeding and weaning of the mothers living in slums areas in Rajshahi, Bangladesh, duration was 8 months from May, 2014 to December, 2014. All the mothers living in slum areas in Rajshahi constituted the study population, sample size was 350 and purposive sampling technique was followed. A partially structured questionnaire duly pre-tested was used to collect data by face to face interview. Results: In this study most (57.7%) of the respondent had two children, (48.6%) mentioned honey as pre-lacteal food, (47.5%) of the respondents told that pre-lacteal feeding was given due to tradition and (49.7%) considered malnutrition as the effect of not giving colostrum’s. Regarding time of weaning, (55.7%) of the respondents mentioned that the babies should be weaned at the time of more than 6 months, hotchpotch (khichuri) was considered as common weaning food consisting of (40.0%). About 49.0% of the respondents considered malnutrition as the effect of improper weaning, most (67.6%) of the respondents considered honey as pre lacteal food and hotchpotch (37.8%) was regarded as the common type of weaning food, most (73.71%) of the respondents knew about pre-lacteal food, weaning was known to almost all (99.14%) of the respondents, pre-lacteal food was given to the baby by majority (73.14%) of the respondents and almost all (99.71%) of the respondents weaned their babies. There was relationship between occupation of the respondent's husband and giving pre-lacteal food to their babies (p < 0.05). Conclusion: Pre-lacteal feeding was found to be more prevalent in slums in Rajshahi. Pre-lacteal feeding activity was closely linked to lower levels of schooling, increased family size, failure to attend ANC, and refusal to feed colostrum. As a result, improving mothers' educational status, reducing family size, encouraging ANC follow-up, and colostrum feeding are all effective ways to avoid prelacteal feeding.