A study was undertaken to ascertain the effects of Trypanosoma murmanensis, on adult longhorn sculpins (Myoxocephalus octodecemspinosus) following experimental infection. Blood samples, taken at intervals after infection, indicated a decrease in hematocrit, hemoglobin and total plasma protein levels which did not return to normal for at least 72 days. An increase of lymphocytic cells occurred about 42 and 58 days but reverted later to normal levels. Anemia persisted despite low parasitemias and might be attributed to lytic factors released directly or indirectly by the parasite and/or an inability of the erythropoietic system to respond following the initial blood loss.