The purposes of this investigation of patients with stroke were to 1) determine and compare shoulder lateral rotation range of motion (SLRROM) measured at the threshold of pain on the paretic and nonparetic sides; 2) establish the intrarater and interrater reliability of the measurements; and 3) determine the relationship between SLRROM measurements and the independent variables of age, sex, and time since onset of stroke. Subjects were 25 rehabilitation inpatients. The two investigators each measured the patients' SLRROM twice on both the paretic and nonparetic sides using a gravity goniometer. An analysis of variance (ANOVA) demonstrated that SLRROM was significantly less on the paretic side than on the nonparetic side (F = 28.98, p less than .001). The ANOVA demonstrated no difference in the two raters' measurements of SLRROM. The intraclass correlation coefficients (ICC[3,1]) and interrater reliability coefficients were all good to high (.874-.989). The SLRROM on the paretic side correlated significantly with time since onset of stroke (r = -.538, p less than .01). As a consequence of this study, we concluded that 1) patients with stroke tend to lose SLRROM on the paretic side, 2) SLRROM tends to decrease with time, and 3) measurements of SLRROM obtained with a gravity goniometer are reliable and sensitive.