Why did isis wear a red dress?

The goddess 3s.t (Isis) is frequently shown with her linen dress dyed red, the ancient Egyptian colour of life, victory, anger, fire and the sun.

Isis was connected with blood, resurrection, eternal life, rebirth, reincarnation and the Sun-Boat or solar barque. Red is an appropriate colour for all these associations.

Isis was not the only goddess to be sometimes shown wearing a red sheath-dress (others include Ma'at, Nephthys, Serket and Hathor), but it was still an unusual appearance and marked her out as special among the many gods of Egypt.