A steam injection project has been conducted in diatomite containing heavy, biodegraded oil (12° API, ∼3000 cp.) in the South Belridge field, Kern County, California. The diatomite interval tested (San Joaquin, Etchegoin, and Belridge diatomite) underlies an active steamflood in the sandstone of the Tulare Formation. Initially, the test was to determine the viability of cyclic steam recovery from an unpropped, steam fractured completion in the diatomite. Four standard steam cycles were completed, with sluggish oil recovery (Oil-Steam Ratios, or OSR's, are less than 0.1). The well was then hydraulically fractured and propped. Two additional steam cycles were completed, with considerably greater oil recovery (OSR's > 0.2). The project was then configured for steamdrive by drilling a closely spaced producer. The new producer was initially completed with a propped hydraulic fracture and cycled once. The original cyclic producer was converted to continuous injection, and a two-well steamflood was operated for greater than one year. During the steamflood, heavy oil has been mobilized and response has been continuous. The configuration of the pattern, with only one producer, results in poor capture efficiency. The performance of this incomplete pattern has been, as expected, poor (<0.1 OSR), but steam injection is shown to be a promising recovery technique for the heavy oil diatomite.