This work gives the attention to a problem of furniture beetles fumingation with formalin. Steams of formaldehyde after four full days of fumingation in temperature of 21°C degrees gave 100% of mortality amongst larvas of furniture beetle, increasing the temperature by 30°C degrees shortened the time of fumingation up to twenty four hours. Formalin is the 40% solution of formaldehyde in water. The main problem is the increase of humidity in gas chamber amounting to 54% at the beginning and going up to relative humidity of 100% within 5 hours. The influence of the steams on gilts and polichromes was also tested. After two weeks of fumingation with formaldehyde there were found dark stains on the gilts. Also on one of polchromed samples there was found resin spil in the spot where the knot was.