Yeasts and yeast like fungi isolated from samples of stored timber scheduled for processing in a sawmill were analyzed. Four series of wood were taken from heartwood, sapwood, and bark of the following timber log species: American basswood, black cherry, black locust, red oak, soft maple, and white poplar. Isolates were identified on the basis of colony and cellular morphology, fermentation of sugars, assimilation of carbon and nitrogen compounds, production of extracellular urease, and reaction with Diazonium Blue-B. Predominant species varied with tree, season, and location. Species of Pichia tended to predominate, particularly in August samples and especially from the sapwood of basswood, locust, and cherry. Candida-sake and other members of group 7 of the genus Candida were common in samples taken in May from the sapwood and heartwood of maple and oak logs. The predominant members of Cryptococcus and Rhodotorula isolated from the samples were Cryptococcus-laurentii and Rhodotorula-glutinis, respectively. The authors conclude that occupational exposure to dusts generated during wood processing may result in significant pulmonary distress and/or injury. There is a need for further characterization of microbial burden during different mill activities.