This protocol describes how to prepare and analyse cassava leaf samples for their total hydrogen cyanide content by the picrate paper method. Cyanide in leaves of crops other than cassava can also be prepared and analysed using this protocol. The picrate paper method for leaf cyanide determination relies on endogenous enzymes to breakdown the cyanogenic glucosides (linamarine) in fresh cassava leaf samples. In this protocol cassava leaves are crushed to bring together the cell contents of cassava leaves, including the enzyme linamarase and the cyanogenic glucosides. Hydrogen cyanide is liberated in the process and it reacts with picrate papers that have a colour pigment which darkens with released cyanide. The variations in the darkening of picrate papers is then used to measure the amount of hydrogen cyanide released from fresh cassava leaf samples. This protocol has been already well outlined by Dr J.H. Bradbury and his team, so please refer to their document (see the attached document below). A kit for cyanide analysis in cassava roots called PROTOCOL E: DETERMINATION OF TOTAL CYANIDE IN LEAVES, has also been designed by them. This protocol describes how the Protocol E kit can be used to determine cyanide in cassava leaves. This protocol is not a replacement of the original protocol. Some of the contents of this protocol have however been directly copied from the original protocol; they are indicated in bold text. This protocol however contains additional insights from things encountered during the use of the kit; this information is in normal text. In addition to this, this protocol includes insights that Dr Bradbury shared to help troubleshoot a few unforeseen issues; these insights are in italics.