Abstract: A thoracentesis device which includes an elongated flexible catheter fixed at its proximate end to an elongated conduit which is aligned therewith. The conduit is provided with a seal which seals around a hollow needle which penetrates the seal means and passes through the conduit and the catheter and slightly beyond the catheter distal end. A vacuum source is connected to the proximate needle end. The seal also reseals the elongated conduit when the needle is removed. The conduit includes a valve which can be manipulated to connect the catheter to a side conduit when the needle is removed.