This study conducted an empirical investigation into the link between market orientation and business performance in the professional veterinary service sector in Thailand. Market orientation was assessed using Narver and Slater’s (1990) construct, adapted to the industry and cultural context of this study. Customer orientation is a key sub-dimension of market orientation, but other components include competitor orientation, inter-functional coordination, long-term focus, and profit emphasis. Data from eighty owners of veterinary clinics and hospitals in Bangkok and suburban areas were used to empirically test the hypothesized relationship between these components and two components of business performance, customer response and financial performance. Regression analysis revealed that customer orientation was a significant determinant of customer response, and to complete the causal chain, customer response had a significant positive effect on financial performance. The customer orientation component is the key element driving the relationship. The implication for high level professional service businesses in general, and veterinary care businesses in particular, is that customer orientation can help them gain competitive advantage and improve business performance.