Effective monitoring, epidemiological assessment and evaluation are necessary to achieve the aim of interrupting LF transmission. The is manual is designed to ensure that national elimination programmes have available the best information on methodologies and procedures for (i) monitoring MDA, (ii) appropriately assessing when infection has been reduced to levels where transmission is likely no longer sustainable, (iii) implementing adequate surveillance after MDA has ceased to determine whether recrudescence has occurred, and (iv) preparing for verification of the absence of transmission. The manual provides general guidance to national programmes; relevant background information on technical issues is contained in the annexes. The first edition of this document was published in 2005. This revised document reflects better understanding of epidemiological aspects of the disease, further field experience, and operational research in monitoring and evaluation of activities to eliminate LF.