Iodinated epidermal growth factor was used to identify its specific receptor in 32 human colorectal carcinomas. The receptor was found in 25% of the tumors with values between 6.9 - 104.0 fmoles/mg DNA. Receptors for estrogen and progesterone were detected in 45 and 25% of the tumors respectively. No correlation was observed between short term survival and content of receptors for sex steroid hormones. Four of the 8 patients with detectable levels of epidermal growth factor receptor had experienced relapse.