This economic evaluation takes the perspective of a health plan provider. The primary objective was to determine if medical expenses of members enrolled in the not-for-profit, US-based Union Pacific Railroad Employes Health Systems (UPREHS) health plan were reduced after implementing a low-cost, patient-focused education campaign on sleep-disordered breathing (SDB). The authors reviewed medical claims records of all members (N=22,275) from 2 years before (2005-2006) and 2 years after (2007-2008) the campaign. Members were assigned to a non-SDB (did not seek diagnosis or not diagnosed with SDB), an SDB-NT (diagnosed with SDB but not on therapy), or an SDB-PAP (diagnosed with SDB and on positive airway pressure [ PAP] therapy) group. The authors assessed overall medical and inpatient hospital costs (calculated as annual per member per month [ PMPM] costs), and number of hospital admissions. The percentage of members with SDB was 11.1% (2350/21,185) in 2005 and 10.5% (2385/22,639) in 2008. During the study, the percentage of members with SDB receiving PAP increased 145% (2005: 23%, 517/2350; 2008: 54.3%, 1265/2385). After the campaign was initiated, overall medical PMPM costs were significantly lower for the SDB-PAP than the SDB-NT group (2007: $572.10 vs. $720.27, P = 0.0006; 2008: $645.66 vs. $846.58, P = 0.0009), resulting in a differential cost savings of $4.9 million for the study period. In addition, inpatient hospital PMPM costs and the number of hospital admissions also were lower for the SDB-PAP group than for the SDB-NT group. These findings suggest that an SDB education campaign can improve health care outcomes and reduce medical expenses. (Population Health Management 2013; 16:7-13)