Technical Abstract: Protein elongation factors, EF-Tu and EF-1a, have been implicated in cell response to heat stress. In spring wheat, EF-Tu displays chaperone activity and reduces thermal aggregation of Rubisco activase. Similarly, in mammalian cells, EF-1a displays chaperone-like activity and regulates the expression of heat shock proteins. We investigated the expression of EF-Tu and EF-1a in mature plants of spring wheat cultivars Kukri and Excalibur and tested the hypothesis that cultivars with contrasting tolerance to heat stress differ in the expression of these elongation factors under prolonged exposure to high temperature [16 d, 36/30°C]. In addition, we investigated the expression of EF-Tu and EF-1a in young plants experiencing a 24-h heat shock (43°C). Excalibur showed better tolerance to heat than Kukri. Heat stress induced accumulation of EF-Tu and EF-1a in mature plants of both cultivars but to a greater extent in Excalibur. Young plants did not show appreciable accumulation of EF-Tu in response to heat shock. However, these plants over expressed EF-1a and the over expression appeared greater in Excalibur than in Kukri. The results support the hypothesis that EF-Tu plays a role in heat tolerance in spring wheat. The results also suggest that EF-1a may be of importance to wheat response to heat stress.