In Heavy Magazine interview, Nergal said that the artwork for album The Satanist contain his own blood.

Russian symbolist painter Denis Forkas was commissioned for the work, with Nergal delivering a box containing his own blood to Moscow where Forkas blended it into the painting to give it "a more organic feel."

In 2012 Łukasz Dunaj published a book titled Konkwistadorzy Diabła (Devil's Conquistadors), which is Behemoth's biography.

In July 2007 the All-Polish Committee for Defense Against Sects distributed a list of bands that allegedly promote satanism and murder to many Polish officials. Critics of this policy primarily see this as a violation of free speech, with the most scathing criticism generally emanating from within the metal community. As of present, the list has not gone into effect, and Behemoth are still allowed to play in Poland freely.

In August 2010 Nergal was rushed to a hospital and was diagnosed with leukemia. It was reported that his leukemia was so advanced that chemotherapy couldn't help him. This was proven wrong. His fiancée Doda offered her bone marrow for a transplant but tests showed she wasn't a match. A donor has since been found. Behemoth were forced to cancel all upcoming shows in August including Sonisphere Festival in Finland, concerts in Russia, Belarus and Baltic States, and their North American tour "Lawless States of Heretika" with Watain, Withered and Black Anvil in November and December.

He has since recovered from the illness.

Nergal has completed six years of history, including one year of Latin at University of Gdańsk, and is qualified to be a museum curator.

Vocalist and guitarist Nergal has been dating Polish pop star Doda (real name Dorota Rabczewska) during 2009. Doda started her career as the vocalist of Polish rock band VIRGIN in 2000, when she was 16 years old. She also posed nude for some adult magazines such as the Polish edition of Playboy and CKM. In 2007 she started a solo career and became one of Poland's most successful pop stars. In January 2010, they became engaged. In March 2011, News.pl reported the couple had called off the engagement and broken up.