The extracted dye from the turmeric was used as a yellow natural dye for dyeing of cotton yarn. The conditions for dye extraction were to extract the turmeric at 60°C for 1 hour with 95% ethanol in 1:4 liquor ratio of the turmeric to solvent. Cotton yarn dyeing with the extracted dye from the turmeric was carried out at 50-60°C for 60 minutes with a material to liquor ratio of 1:20. The effect on dyeing of mordant type with different mordanting methods was studied. The results showed that the dyeing of cotton yarn using the pre-mordanting with alum provided better percentage of exhaustion than with other mordants (ferrous sulfate, copper sulfate) or without a mordant. The cotton yarn treated with pre-mordanted by alum was moderate of the wash fastness property.