BACKGROUND: During operative laparoscopy, large (10 mm or more) ancillary ports are often used for instrumentation and tissue removal. Although sharp pyramidal trocars can be used to place these ports, their use appears to increase the risk of vessel injury and herniation. We describe a simple and cost-effective technique for converting a 5-mm port to a 10- or 12-mm port using a blunt conical trocar. TECHNIQUE: When a larger port is required, a previously placed 5-mm port is removed, and the skin incision is lengthened. A reusable 10- or 12-mm blunt conical trocar with a threaded sleeve is placed through the incision. The fascial defect is located by probing and is dilated gently with the blunt tip. Once the tip is through the fascia, it is advanced through the peritoneal defect with a clockwise, twisting motion. Afterwards, the fascial defect is closed with a single, interrupted absorbable suture. EXPERIENCE: We have had no complications or difficulty when using this technique in 26 cases, either during or after surgery. CONCLUSION: A reusable blunt conical trocar is a simple, safe, and cost-effective instrument for converting a 5-mm laparoscopic port into a 10- or 12-mm port.