During a study on testicular cycle in the tropical teiid lizard Cnemidophorus 1. lemniscatus (L.), some animals showed testicular haemorrhagic suffusions presumptively due to traumata suffered while they were captured, between 4 and 8 hours before the autopsy. Their testes were immediately removed and processed to be examined under the light microscope. The extravasated blood was always relatively scarce and limited to the interstitial spaces. Numerous multinucleate spermatogenic cells in all the stages of development were found within the seminiferous tubules contiguous to the suffered blood. The number of nuclei in these cells increases from spermatogonia, which generally have two and rarely more than four, to spermatids, which sometimes form giant cells with more than thirty nuclei. The various nuclei of each multinucleate cell pertain exactly to the same spermatogenic stage. Divisionss of the multiple nuclei proceed simultaneously but in an independent way. As relatively broad intercellular bridges between normal spermatogenic cells of each type can be seen in this species through the electron microscope, cell fusion by enlargement of the preexistent cytoplasmic interconnections is considered to be the more probable way of formation of multinucleate cells. Nuclear divisions not followed by cytokinesis may contribute in this process. A reduced exchange of materials derived from the local circulatory disturbance, and particularly hypoxia, are likely the cause of these cell alterations.