1AbstractAnalysis of limited and nonlimited emissions of scooters was performed during several research programs of the Swiss Federal Office of Environment Forests and Landscape (FOEFL) - and as a contribution to the European project ARTEMIS*).Small scooters, which are very much used in the congested centers of the European cities are a remarkable source of air pollution. Therefore every effort to reduce the emissions is an important contribution to improve the air quality in urban centers.In the present work detailed investiga-tions of a Peugeot scooter with TSDI (Two Stroke Direct Injection) were per-formed and the emissions were compa-red to the other 2-S & 4-S scooters.As nonlimited emissions the nanopar-ticulate emissions at cold and warm operating conditions were measured by means of SMPS, ELPI and NanoMet*). The measurements were both: at steady state and at transient operating conditions.It can be stated, that the TSDI-technology offers advantages of lower gaseous and particulate emissions. It reaches about the level of 4-S vehicles.Since the particulate emission of the 2-S consists mainly of lube oil conden-sates the minimization of oil consumption stays still an important goal. Further improvements of oil & fuel quality, as well as optimisation of catalysts can also contribute to a reduction of particulate matter and particle counts.