A 47-year-old woman was pricked accidentally with a needle previously used for a neurosyphilitic man. At day 0 she had no positive laboratory results for the infection, while the source, at day 1, had TPHA positive, but no post-exposure prophylaxis (PEP) against syphilis was prescribed. The subject missed the day 30 follow-up, and underwent our visit at day 90, when she showed no clinical signs, but she seroconverted (VDRL = positive 1/2; TPHA = positive 1/320; FTA-Abs IgG and IgM = present). She started antibiotic therapy, and currently her serological status is VDRL = positive 1/2, TPHA = positive 1/160, FTA-Abs IgM = negative.