HANOI, Vietnam — It was midnight here in Hanoi, or already 2 a.m. back in Seoul, South Korea. But after a five-hour flight on a recent Sunday, Kim Wan-su was driven straight from the airport to the Lucky Star karaoke bar here, where 23 young Vietnamese women seeking Korean husbands sat waiting in two dimly lighted rooms.

“Do I have to look at them and decide now?” Mr. Kim asked, as the marriage brokers gave a brief description of each of the women sitting around a U-shaped sofa.

Thus, Mr. Kim, a 39-year-old auto parts worker from a suburb of Seoul, began the mildly chaotic, two-hour process of choosing a spouse. In a day or two, if his five-day marriage tour went according to plan, he would be wed and enjoying his honeymoon at the famed Perfume Pagoda on the Huong Tich Mountain southwest of here.

More and more South Korean men are finding wives outside of South Korea, where a surplus of bachelors, a lack of marriageable Korean partners and the rising social status of women have combined to shrink the domestic market for the marriage-minded male. Bachelors in China, India and other Asian nations, where the traditional preference for sons has created a disproportionate number of men now fighting over a smaller pool of women, are facing the same problem.