OBJECTIVES: The MFSAF Diary is a refined version of the Myeloproliferative Neoplasm Symptom Assessment Form (MPN-SAF) designed to measure the impact of MF-related symptoms. Six symptoms are rated on a scale from 0 (absent) to 10 (worst imaginable): 1) night sweats; 2) itching (pruritus); (3) abdominal discomfort; 4) filling up quickly when you eat (early satiety); 5) pain under ribs on left side; and 6) bone or muscle pain. The objective of this study is to present the development of a generic Spanish version to be used in Mexico, Spain, and the USA. METHODS: 1) Concept definition; 2) Development of a Spanish translation in Mexico, Spain, and the USA; 3) Creation of a reconciled Spanish version using the three Spanish versions as a basis; 4) Backward translation of the reconciled version; 5) Cognitive interviews with five patients in each country. RESULTS: The development of the reconciled version did not show major difficulties. For instance, “bone or muscle pain” was translated as “dolor en los huesos o músculos,” and well understood by patients. It was agreed that the use of nouns (huesos/musculos for bones/muscles) was more appropriate as people with a very low education level might have difficulties to understand adjectives such as “óseo” (osseous). Patients had difficulties with “itching (pruritus)” translated at first by “comezón/prurito/picor.” It was impossible to find a common term for the three countries, and a compromise was found with the use of the association of “comezón/picor,” with “comezón” widely used in Mexico and “picor” in Spain. “Prurito” could not be chosen for all countries since it was problematic for Spanish patients. CONCLUSIONS: The creation of a generic Spanish version of the MFSAF Diary was made possible by developing Spanish versions in Mexico, Spain, and the USA, and accepting compromises when common terms could not be used.