OBD may stand for:
- On-board diagnostics, an electronics self diagnostic system.
- On Board Device (disambiguation), any vehicle management electronic hardware.
- Optimal Biological Dose, the quantity of a radiological or pharmacological treatment that will produce the desired effect with acceptable toxicity.
- Outbound Dialler, and automated calling mechanism that plays a pre-recorded message and allows people to respond by pressing numeric keys on their mobile phone.