One of the most critical areas of research essential to improve the clinical use of hyperthermia in cancer therapy is the determination and evaluation of temperature during therapy. In order to improve the dissemination of newly developed thermometry measurement and analysis programs and facilitate the transport of hyperthermia data files between computers for both intra- and inter- institutional use, we propose a standard file format, the Hyperthermia Data Standard (HDS), which can be used for all hyperthermia data. This data file consists of segments of which nine have been defined. The first is an initial /VERSION segment which identifies the file standard. This is followed by eight major segments: 2) a /IDENT segment which contains file and patient identification information; 3) a /TEXT segment containing additional miscellaneous documentation; 4) a /TUMOR segment which provides tumor and treatment site information; 5) a /HSETUP segment which contains treatment setup information; 6) a /FORMAT segment which defines the data segment structure; 7) a /DATA segment containing the actual thermometry data; 8) a /FOLLOWUP segment for documenting patient response; and 9) an /ANALYSIS segment containing summary information. All segments begin and end with a specified delimiter and, except for the first two (/VERSION and /IDENT), may be repeated more than once. For ease in debugging and verifying adherence to the standard, all information in the file is encoded in printable ASCII characters. All segments consist solely of records containing KEYWORDS and KEYWORD VALUES which identify specified information. Certain KEYWORDS are standard, i.e., having specified names and information formats as defined in this document. The /DATA segment consists of ASCII encoded chronological treatment thermometry and other data whose format and structure is identified in the /FORMAT segment. The /ANALYSIS segment provides the flexibility to store the results of any analysis program along with the actual data file for ease of data management. This thermometry data file standard is designed to provide both flexibility and extendability for all possible forms of hyperthermia treatment data. Furthermore, it is designed to provide a simple format which may be easily read by higher level languages. This document is intended for commercial manufacturers and others who are writing programs to document clinical hyperthermia treatments with the intention that they either use this format for their data storage or provide a means to convert their data into this format.(ABSTRACT TRUNCATED AT 400 WORDS)