Background It is recommended that blood pressure should be measured on a bare upper arm with an appropriately sized cuff. However, in practice, it is more convenient to measure blood pressure on sleeved arms. Aims We aim to examine the effect of sleeved arms on the accuracy of blood pressure measurement. Methods Patients aged 18 years or older were enrolled. Participants underwent three blood pressure measurements in each of the following sleeve conditions in random order (bare arm; arm covered with a single-layer cotton shirt sleeve,1 mm; arm covered with two layers sleeve containing a cotton shirt and a polar fabric sweater, 3 mm; arm covered with two layers sleeve containing a cotton shirt and a thick cardigan, 4 mm). Results Of the 300 participants, 155 (52%) were men. The mean age was 62.9 (10.7) years, and 226 (75%) had hypertension. There were no significant differences in either systolic blood pressure or diastolic blood pressure among the four kinds of sleeve conditions in all the participants (P > 0.5), and the mean blood pressure differences between measurements made on the sleeved arms and bare arm were within 1.0 mmHg. Blood pressure of sleeved arms was positively correlated with that of the bare arm (P < 0.001; r > 0.95), and showed good consistency. Conclusions In the present study, we concluded that there was no significant effect of sleeved arms on the accuracy of blood pressure measurement by using an electronic oscillometric sphygmomanometer equipped with a conventional cuff.