The relationship between subjective evaluation of slipperiness and objective measures of a slipping hazard was examined. The study group consisted of 33 male iron workers, mean age 34.9 years, experienced in walking and climbing on steel surfaces and 23 university students, mean age 24.1 years, with no ironworking experience. The subjects walked or climbed on steel beams and columns coated with one of three types of paint or uncoated and which were contaminated with water, clay, or an oil and plastic sheet combination. The subjects rated the slipperiness of the surfaces according to a subjective rating scale. The slipping hazard of the surfaces was measured objectively by determining the coefficients of friction (COFs) using a specially designed shoe and sled apparatus. The COFs of the test surfaces ranged from 0.20 to obtained by the experienced subjects were well correlated with the COFs of the surfaces, correlation coefficient 0.89. Among the inexperienced subjects, slipperiness ratings were well correlated overall with the COFs, correlation coefficient 0.90. None of the subjects slipped on surfaces having COF 0.41. Some inexperienced subjects slipped on surfaces having COFs of 0.20. The authors conclude that subjective differences in slipperiness of the surfaces studied can be identified. The COF threshold for loss of footing on the surfaces appears to be less than 0.40 but greater than 0.20.