The results and recommendations of a NIOSH investigation into the deaths of two dairy farm laborers in a manure pit were presented. The two workers, brothers in their 30's working on their father's farm, were attempting to clear a clogged manure waste pipe. The 6 inch diameter pipe was located at the bottom of a 12 foot (ft) by 12ft, 4.5ft deep pit within a small, unventilated room adjoining a dairy barn. The equipment had been in use for 10 years, with corrosion in the pipe resulting in blockages. One worker entered the manure pit which contained 3ft of manure to unclog the pipe while the second worker remained outside the pit. The first worker soon collapsed due to lack of oxygen, and the second worker attempted to assist him. The second worker was also overcome. They were discovered submerged in the manure pit, and were pronounced dead at the scene. The cause of death was determined to be drowning. Preventive measures recommended included owner awareness of the hazards of oxygen poor areas in confined spaces, elimination of the need for entry, posting of warnings in the area, use of ventilation equipment, and education of workers concerning safe procedures and use of protective equipment. The use of noncorrosive materials in the manufacture of manure pumping equipment could reduce the need for maintenance. The development of task specific safety guides for hazardous farm equipment and operations was also recommended.