Laser assisted thrombolysis may be a viable alternative or adjunct to current thrombolytic therapies. However, knowledge of the particulate debris associated with this modality is limited. The objective of this in-vitro study was to evaluate and quantify the particulate generation following ablation of thrombus. Ablation of reconstituted thrombus was conducted in-vitro with an excimer laser operating at 308 nm and multifiber laser catheters. Particulate debris was quantified by weighing filtered particles and light obscuration particle counting. The effect of laser parameters, catheter size, and clot consistency on particulate production and ablation efficiency was investigated. For light obscuration particle counting experiments, the total number and size distribution of particles was similar for all laser parameters. More than 92% and 99% of the particulate generated was less than 10 and 25 microns, respectively. For the filtering experiments, particulate greater than 10 microns amounted for less than 6% of the original clot weight. Increased catheter size, increased laser parameters, and decreased clot consistency produced greater amounts ablated without increasing particulate debris production. The majority of particulate produced by excimer laser ablation of thrombus in-vitro was sub-cellular in size and debris production was not influenced by laser parameters, clot consistency, or catheter size.