Abstract The Specific Leaf Area (SLA) is defined as the area per unit of weight of the leaf. SLA is a physiological parameter used in agronomy. In our experiment, ten varieties of rainfed rice were selected for its determination by using either a whole leaf or a foliar disc of rather large size (1,328 cm2); its value decreases according to the position of the leaf upwards of the stem. It is an architectural parameter depending on the area and on the foliar architecture. Leaves with high SLA are thin, the plant has a strong tillering and is ta ll; on the other hand those which have a low SLA are of small size and have thick leaves. Depending on the phenologic stage of the plant, the SLA is high at the vegetative stage (tillering) during which the leaf area is wide but the foliar dry weight is low; the plant is in full vegetative growth and tiller development. At the reproductive stage, the SLA decreases, the leaf area remains constant but the dry weight increases. Assimilates and synthetates ensure the development of the reproductive organs of the plant. At the maturity stage, it decreases quickly due to the senescence of the leaf but the foliar dry weight increases because of the degradation and the accumulation of the dry matters in the leaves; leaves with weak SLA have high SPAD (Soil Plant Analysis Development) values. The SLA is positively correlated with the LAI.