Real-time, on-body measurement using minimally invasive biosensors opens up new perspectives for diagnosis and disease monitoring. Wearable sensors are placed in close contact with the body, performing analyses in accessible biological fluids (wound exudates, sweat). In this context, a network of biosensing optical fibers woven in textile enables the fabric to measure biological parameters in the surrounding medium. Optical fibers are attractive in view of their flexibility and easy integration for on-body monitoring. Biosensing fibers are obtained by modifying standard optical fibers with a sensitive layer specific to biomarkers. Detection is based on light absorption of the sensing fiber, placing a light source and a detector at both extremities of the fiber. Biosensing optical fibers have been developed for the in situ monitoring of wound healing, measuring pH and the activity of proteases in exudates. Other developments aim at the design of sensing patches based on functionalized, porous sol-gel layers, which can be deposited onto textiles and show optical changes in response to biomarkers. Biosensing textiles present interesting perspectives for innovative healthcare monitoring. Wearable sensors will provide access to new information from the body in real time, to support diagnosis and therapy.