This study investigated the nutritional effect of sunflower seed protein fraction (SSPF) extracted with isopropanol on growth, plasma and tissue lipid profile, protein content and erythrocyte membrane lipid profile of rats. Dehulled sunflower seeds were extracted with isopropanol at 50 ± 1 °C resulting in a protein fraction (71.5%) with low residual chlorogenic acid (0.07%) and fiber (3.3%) contents. Rats fed the sunflower seed protein fraction had a similar body weight gain and food efficiency ratios in comparison to those fed casein. Rats fed SSPF in contrast had a significantly higher growth and food efficiency ratio than the rats fed sunflower meal (SM), extracted with hexane. However, dietary proteins exerted a separate effect on plasma total cholesterol, low density lipoprotein (LDL)-cholesterol, low density lipoprotein to high density lipoprotein cholesterol (LDL-C/HDL-C) ratio and triglyceride content. Sunflower seed protein fraction resulted in a significant decrease in plasma cholesterol (p < 0.05) and LDL-cholesterol (p < 0.02) levels compared to the casein fed rats. Membrane phospholipid profile also showed a marked variation with the type of dietary protein. Rats fed SSPF and SM did not show much variation in plasma lipids, plasma proteins, liver and brain lipids and membrane phospholipid concentrations. Protein content, liver and brain lipid profile of the groups fed SSPF and casein were comparable, suggesting that the nutritional value of SSPF is better than SM and equivalent to that of casein.