To determine if anesthetic agents used in laboratory animal euthanasia affected sperm motion parameters, rats (n = 10 per group) were euthanized by one of 5 different methods: decapitation alone, or decapitation following either ether, halothane, or Nembutal anesthesia, or CO2 asphyxiation. Sperm were collected from the distal cauda epididymis, diluted, and videotaped for computer-aided sperm analysis (CASA; HTM-2030, Hamilton-Thorn Research, Beverly, MA). The percentage of motile sperm (MOT), their straight-line velocity (VSL), average path velocity (VAP), curvilinear velocity (VCL), linear index (LINX), and linearity (LIN) were measured on greater than or equal to 200 motile sperm per sample. No significant differences in any of these 6 motion parameters were found among the treatment groups. Thus, none of these 5 methos of euthanasia affect sperm motion as assessed by CASA methods, making them equally suitable for use in reproductive toxicology studies. (Copyright (c) 1994 Elsevier Science Ltd.)