A virtual tour in laser spectroscopy and trace gas detection laboratories. First, laser instruments developed for high-resolution molecular spectroscopy are shown, including a new infrared optical frequency comb that also produces several visible laser wavelengths. The applications include both fundamental molecular spectroscopy and trace gas detection. In the second laboratory, we see an online mass spectrometer that is based on proton transfer reaction mass spectrometry. This instrument is used, for example, for real-time analysis of human exhaled breath. Novel breath tests are developed for non-invasive medical diagnostics and biomonitoring.