In this study, the overall prevalence of exclusive breastfeeding among mothers with infants up to six months of age was 43.1%. This result was higher compared to the national figure [2]. Other studies reported prevalence of exclusive breastfeeding between 12.5% and 48% [15-17]. Under the Malaysia National Study, a 24 hour recall period was used. The WHO has developed a set of definitions and indicators of infant feeding patterns that can be applied in assessing breastfeeding practices in household surveys using the 24 hour recall methodology [18]. In this study, data on breastfeeding was based on feeding practice over a period of one month prior to the interview which is a non-standard practice to collect breastfeeding data. The validity of data on exclusive breastfeeding based on 24 hour periods has also been questioned [19]. Aarts et al. reported a wide discrepancy on the prevalence of exclusive breastfeeding between current status based on a 24-hour recording and exclusive breastfeeding since birth [20]. Several factors may have led the study to overestimate the prevalence of exclusive breastfeeding of the population. Since the interview was conducted face-to-face, by the author who is a medical doctor, in the health clinics which strongly promote exclusive breastfeeding, information bias is possible. A recall period of one month may lead to recall bias among respondents. The majority of the respondents were Malays, of low family income and not working. Selection bias may have occurred as studies have showed that these factors were strongly associated with exclusive breastfeeding in Malaysia [2,15-17].