First toe systolic blood pressures (FTSBP) before and after first toe cooling were measured with the laser Doppler method in 17 normal women and 10 female patients with primary Raynaud's phenomenon (PRP). The room temperature was maintained at 26 degrees C. There was no significant difference in toe-arm systolic blood pressure ratio between the two groups. After toe cooling at 10 degrees C, the PRP group had a significantly greater reduction in FTSBP than the normal group. Measurement of FTSBP before and after toe cooling is a useful method for assessing Raynaud's phenomenon in the toes of patients with PRP.