Eugen Woldemar Bostroem (October 13, 1850 – May 24, 1928) was a German pathologist. He was a native of Fellin (nowadays Viljandi), Livonia).
He studied medicine in Leipzig and Erlangen, receiving his degree in 1876. Afterwards he was an assistant to Friedrich Albert von Zenker (1825-1898) at the pathology institute in Erlangen. From 1883 to 1926 he was a professor of general pathology and pathological anatomy in Gießen.
In 1890 Bostroem reportedly isolated the causative organism of actinomycosis from a culture of grain, grasses, and soil. After Bostroem's discovery there was a general misconception that actinomycosis was a mycosis that affected individuals who chewed grass or straw. The agents of actinomycosis are now known to be endogenous organisms of the mucous membranes, in most cases Actinomyces israelii, a species named after surgeon James Israel, who first discovered its presence in humans in the late 1870s.
In 1883 Bostroem was the first to describe a rare condition known as splenogonadal fusion. Since his discovery, approximately only 150 cases have been documented.