In many institutions, spinal anesthesia is used for surgery involving ultrasonically guided transvaginal oocyte retrieval. Because this relatively short procedure is performed on an outpatient basis, the optimal spinal technique would allow good surgical anesthesia with a short recovery time. The relative regression of equal doses of different concentrations of hyperbaric spinal lidocaine is presented. We compared 1.5% and 5% hyperbaric lidocaine (7.5% dextrose) as spinal drugs for use in this procedure. Fifty-six patients were randomized to receive 60 mg of hyperbaric solutions of either 1.5% or 5% lidocaine in combination with 10 micrograms of spinally administered fentanyl. Visual analog scale pain scores were zero throughout the procedures for all patients. There were no significant differences between the groups with regard to sensory level, maximum motor block, intravenous sedation requirements, time to two-segment regression, and time to full sensory recovery. The group receiving 1.5% lidocaine had significantly shorter times to ambulation (141 +/- 21 min vs 162 +/- 29 min; P < 0.05), voiding (147 +/- 21 min vs 174 +/- 28 min; P < 0.05), full motor recovery (86 +/- 21 min vs 111 +/- 22 min; P < 0.0001), and discharge (170 +/- 38 min vs 201 +/- 41 min; P < 0.05). The use of 1.5% hyperbaric lidocaine for transvaginal oocyte retrieval provides a significantly shorter recovery time when compared to 5% hyperbaric lidocaine and is a good choice for spinal anesthesia for this procedure. Manica, Bader, Fragneto, Gilbertson, Datta, , , , (1993). Anesthesia for in vitro fertilization: a comparison of 1.5% and 5% spinal lidocaine for ultrasonically guided oocyte retrieval. Anesthesia and analgesia, 1993 Sep;77(3):453-6. https://www.ncbi.nlm.nih.gov/pubmed/8368544