In this study, medical equipment life by bath-tab curve is analyzed, and the validity and reliability of the maintenance inventory of medical equipment is examined. A total of 7, 030 repair reports were extracted from maintenance inventory of medical equipment between 1988 and 2003, as records for the study. An indication of early failure period was mean time to first failure (MTTFF). An indication of random failure periods for exponential distribution were mean time between failures (MTBF) and MTBF (low), The internal consistency for medical equipment was analyzed using X^2 confidence level 90%. An indication of wear-out failure periods for normal distribution were mean time to repair (MTTR), steady availability, and maintenance cost (average, standard deviation). MTTFF of early failure period was 1.5 year. MTBF and MTBF (low) of random failure periods were a year, and half year, respectively. Maintenance cost, MTTR and steady availability of wear-out failure periods were 120, 000 yen, 9.5 day, and 100.5%, respectively. The result indicated the effectiveness of preventive maintenance for medical equipment. This study shows that the wear-out failure, random failure and early failure periods of medical equipment life by bath-tab curve.

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