Rice is second most consumed cereal after wheat and it is considered as staple food in Thailand and most of the ASEAN countries. Analyzing yield performance of upland rice genotypes under field conditions is a key step in rice crop breeding program for improved rice production and ensuring food security. The objective of this research was to conduct a yield trial to assess performance of sixteen Thai upland rice genotypes under field conditions for further breeding process. Data from field trial that was conducted in 2016 in field research area of Faculty of Natural Resources, Prince of Songkla University, Hat Yai, Thailand was used in this assessment. Randomized complete block design (RCBD) with three replications was used to layout the experiment in field. Soil was analyzed upto 50 cm soil depth for its fertility and nutrient status to check the fertilizer requirements before planting. Soil moisture contents were recorded using PR2/6 probe. Observed moisture contents indicated that there was 60-70% water available to all genotypes based on filed capacity (FC). Results indicated that genotypes, Hawm Mali Doi, Jao Khao Pichit, Jao Daeng, Sahm Deuan and Ma-led-nai-fai were shorter in plant height while genotypes Ma-led-nai-fai, Goo Meung Lung, Jao Daeng, Dawk Pa-yawm and Hawm Jet Ban had higher number of tillers m-2. Genotypes Ma-led-nai-fai, Goo Meung Lung, Jao Daeng, Dawk Pa-yawm and Hawm Jet Ban had higher number of panicles m-2. Genotypes Jao Daeng, Ma-led-nai-fai, Sahm Deuan, Hawm Mali Doi and Jao Khao Pichit were early flowering and maturity considering as early maturity genotypes. Genotypes Goo Meung Lung, Hawm Mali Doi, Jao Khao Pichit, Jao Daeng and Mai Tahk had higher 1000 GW while genotypes Dawk Kham, Dawk Kha, Hawm Jet Ban, Dawk Pa-yawm and Bow Leb Nahag were superior in grain yield response. Performance of genotypes indicated that these genotypes can be used for further breeding process for acquiring desired traits.