SSIIa gene controls gelatinization temperature in rice. Nucleotide variations at position 4,198 and 4,329-4,330 of SSIIa gene were investigated in 49 cultivars of Thai rice. At position 4,198, only nucleotide G was found, whereas nucleotide GC or TT were found at positions 4,329-4,330. When study correlations between SSIIa gene and cooking and eating quality indices such as gelatinization temperature, amylose content and gel consistency revealed that nucleotide patterns of SSIIa gene correlated with gelatinization temperature (p < 0.01) and amylose content (p < 0.01). Cultivars harbouring GC tended to have medium gelatinization temperature and high amylose content, while TT-genotype cultivars were inclined to have low gelatinization temperature and amylose content. In addition, a positive correlation between gelatinization temperature and amylose content was found (p = 0.016). Cultivars showing low gelatinization temperature tend to have low amylose content and vice versa. Gelatinization temperatures of rice cultivated in season and off season were significantly different (p = 0.047) this may attribute to environmental effect during growing season and storage period.