Several studies have shown effectiveness of SMS interventions to improve health workers’ practices, patients’ adherence to medications and availability of health facility commodities. To inform policymakers about the feasibility of facility-based SMS interventions, the coverage data on mobile phone ownership and SMS use among health workers and patients are needed. In 2012, a national, cross-sectional, cluster sample survey was undertaken at 172 public health facilities in Kenya. Outpatient health workers (219) and caregivers of sick children and adult patients (1,177) were interviewed. Mobile phone ownership and SMS use are ubiquitous among Kenyan health workers in the public sector. Among the patients they serve, phone ownership and SMS use are lower, and disparities exist with respect to gender, age, education, literacy, urbanization and poverty. Some of the disparities in SMS use can be addressed through mHealth interventions and enhanced implementation processes, while further growth in mobile phone ownership is needed to reduce the gap.