Test – retest reliability and validity of knowledge assessment tool on childhood poisoning among mothers .The objectives were examine the validity and reliability of tool to assess the knowledge questionnaires of childhood poisoning among mothers of under–five children. Non probability convenient sampling technique with the sample of 95 mothers was included; structured interview schedule were used to assess the knowledge. The collected data was tabulated and analyzed by using descriptive and inferential statistics. The mean value, standard deviation was 36 and 126.8 respectively. The reliability score of structured interview schedule was 0.69 and which represent the positive correlation, indicates that the tool is highly reliable, so that knowledge assessment tool on childhood poisoning among mothers can be used as validated tool to conduct a research project in future.