The successful and sustainable development of inbound tourism necessitates a long-term commitment, balancing between tourism supply and tourist demands. This study manipulated a performance appraisal of tourism service quality in Taiwan with Data Envelopment Analysis (DEA) by employing input and output constructs to assess service quality efficiency. The empirical results of the estimation of technical efficiency (TE) revealed that (1) the domestic tourism market is competitive, but still needs enhancements for tourism service; (2) Mainland Chinese tourists had the highest score among all foreign tourists, followed by Hong Kong and Macau tourists, tourists from other countries, Japanese tourists, and South Korean tourists; and (3) South Korean tourists had higher travel expenditure than others, but felt less satisfaction with travel services, which can be regarded as inefficient. Tourists from other countries had lower travel expenditure, but had higher satisfaction levels, which was considered efficient based on input and output index. The findings could contribute to bridging the gap between research and practice in assessing the efficiency of inbound tourist service. Tourism practitioners should be aware of tourists' needs and interests, as these could be key fundamentals for improving tourists' satisfaction with Taiwan's service offerings.