Improvements in its tourism sectors have encouraged Lao PDR to explore export options for its traditional waxy rice varieties. Researchers and agriculturists are now exploring ways to enhance the yield and capture high-quality traits of traditional Lao varieties, into popular improved varieties. In this study, the effects of nitrogen (N) on yield and quality traits were investigated for two traditional varieties, Hom Nang Nouane (HNN) and Kai Noy Leuang (KNL), and in two popular improved varieties, Thadokkham-1 (TDK1) and Thasano-1 (TSN1). The varieties were grown during the 2006 wet season at the Rice and Cash Crop Research Center in Vientiane Municipality, Lao PDR. The varieties were grown under four N rates of NPK: 0-30-30 kg/ha, 30-30-30 kg/ha, 60-30-30 kg/ha and 90-30-30 kg/ha. The results showed that while the two improved varieties TDK1 and TSN1 responded to increasing rates of N application that the yield of two improved varieties were increased from 3,000 kg/ha to 4,500 kg/ha about 40% increasing, the two traditional varieties, HNN and KNL, were not as responsive, only increasing from 3,600-3,900 kg/ha. In contrast, the quality traits: aroma, textural (hardness and stickiness), gelatinisation temperature, and viscosity assessed in this study of the four varieties were not affected by N. Yield and textural attributes further suggested that TSN1 is a better candidate than TDK1 for breeding programs aimed at combining quality traits from HNN and KNL, into improved varieties.