To understand the perceptions and attitudes about privacy safeguards in research and investigate the impact of letter-based proband-initiated contact on recruitment, we surveyed researchers in the Siblings With Ischemic Stroke Study (SWISS). All 49 actively recruiting sites provided at least 1 response, and 61% reported that potential probands were enthusiastic. Although 66% of researchers valued proband-initiated contact, only 23% said that probands viewed this strategy as important to protecting the privacy of siblings. A substantial minority of researchers (37%) said the strategy impeded enrollment, and 44% said it was overly burdensome to probands.