The investigations of two incidents in which farm workers died after entering manure waste pits in Minnesota were summarized. The first incident occurred on August 8, 1992, when a 27 year old employee of a hog farm entered an outdoor manure pit to free a clogged pump intake in the pit. The man was overcome, and his uncle entered the pit to assist him and also was overcome. Both men were pronounced dead from hydrogen-sulfide (7783064) poisoning. When the atmosphere in the pit was subsequently tested, no measurable hydrogen- sulfide was reported. Weather conditions were different on the test day than on the day of the incident. In the second incident a 43 year old dairy farm owner and his 23 year old son died from asphyxiation after entering one of two adjacent manure waste pits underneath a barn. Apparently the men were using a pump located outside the barn to pump manure from the pits into the tank of a manure spreader. The father removed a steel grate cover, descend a ladder into the nearly empty pit, where he was overcome as he began to clear an obstruction. His son was found on top of him, apparently overcome during a rescue attempt. They both died of asphyxiation. An extensive editorial note discussed confined space hazards, confined space fatalities during rescue attempts, the contribution of weather conditions to the generation of gases in manure pits, and prevention of fatalities in manure waste pits.