This paper examined the research of Korean scientist Sin Kyu Hyun on x pinus rigitaeda and its influence on forest tree breeding in Korea. Due to his development of hybrid pine rigitaeda, Sin Kyu Hyun achieved fame in the world's and in Korea's scientific community. It was not Sin Kyu Hyun who first accomplished the successful hybridization of pine rigida and teada, or who first acquired hybrid rigitaeda. Nevertheless, he should be considered the first developer of hybrid rigitaeda because he systematically studied the hybrid pine and proved its potential superiority as a forest tree. Sin Kyu Hyun endeavored to plant hybrid rigitaeda widely in Korea. Although his applied research on the hybrid pine was successful in many respects, the spread of hybrid rigitaeda, however, was restricted to a small territory in the south. Eventually, Sin Kyu Hyun's research on pine rigitaeda became partly successful and partly a failure. In the process of his research, Sin Kyu Hyun promoted forest tree breeding as a new academic field, and, as a result, forest tree breeding was actually started in Korea. Various factors, however, made it difficult to spread hybrid rigitaeda. These factors remain unresolved to this day.