Methods and systems for monitoring compliance of a patient with a prescribed treatment regimen are described. Patient activity is detected unobtrusively with an activity sensor at the patient location, and activity data is transmitted to a monitoring location. Patient speech detected during use of a communication system such as a mobile telephone by the patient may also be used as an activity signal. Patient activity and/or speech is processed at the patient location or monitoring location to identify activity parameters or patterns that indicate whether the patient has complied with the prescribed treatment regimen. The activity sensor and other components at the patient location may be incorporated into, or associated with, a cell phone, computing system, game system, or vehicle system, for example. The system may provide a report to an interested party, for example a medical care provider or insurance company, regarding patient compliance with the prescribed treatment regimen.