Abstract: Blood analysis is carried out using a portable video camera with an objective lens, by placing the video camera such that the objective lens is completely obstructed, at least partly by at least part of an appendage forming part of an individual, and operating the video camera. The image signals from the video camera are then analysed to deduce information about blood flow in the appendage. This information may concern blood flow (e.g. pulse rate) or blood constituents. The video camera may form part of a mobile phone, and the objective lens may be completely obstructed by a fingertip. The resulting data may be displayed in real-time on the mobile phone.