In 1985 a program for the improvement of sweet potato (Ipomoea batatas (Lam) L) was funded by ACIAR. This manual has been written as a consequence of that research. Primarily the manual introduces techniques developed for disease elimination and pathogen-testing of sweet potato plants. It then outlines these techniques in detail discussing their possible strengths and limitations. The techniques have been developed and utilised over the duration of the program in the Kingdom of Tonga, Solomon Islands, Papua New Guinea, Western Samoa and Fiji. This report is designed to facilitate the transfer of knowledge, to explain the background of the techniques as well as exposing their limitations, and to discuss the interpretation of results.