This is the fourth annual report of the Swedish Butterfly Monitoring Scheme, a national monitoring programme coordinated by Lund University for the Swedish Environmental Protection Agency since 2010. The programme is a partnership between the Entomological Society of Sweden, the Swedish Environmental Protection Agency, Lund University, the Swedish University of Agricultural Sciences and the Swedish County Administration Boards. The monitoring scheme is volunteer-based and runs from April 1st to September 30th annually. Sites are visited 3-7 times per season and are surveyed using a standardized, common methodology. Two different recording methods are used in the Swedish Butterfly Monitoring Scheme. One is the point site counts which cover an area with a 25 m radius for 15 min per visit. The other method is fixed-route Pollard walk transects, typically 0.5-3 km in length. These two methods enable the monitoring scheme to assess yearly changes both in the number of butterflies seen and in species composition. The fourth year’s monitoring has produced butterfly data from 162 fixed-route walks and 217 point sites, representing a 20% increase in the number of transects and a 7% increase in the number of point sites. The sites and walks are located across the whole country, from Beddingestrand in the South to Vuollerim in the North. In 2013, 269 volunteer recorders participated in the Swedish Butterfly Monitoring Scheme and have counted 65967 butterflies of 91 different species. On average, 12.7 species have been observed at the point sites while 18.4 have been observed along transects. In this report, observations from 2013 of each species are shown as total counts, distribution maps, and flight period histograms. The most numerous species in 2013 was the Ringlet, followed by the Meadow Brown and the Green-veined White. Trends between 2010 and 2013 have been analysed for 90 butterfly and burnet moth species using the analytical tool TRIM. Over the period, 27 species declined and 12 increased. Trends for the remaining species were uncertain. Summarizing indices, so called indicators, have been calculated for 1) the 20 most common species and 2) the 12 Swedish grassland butterflies that are part of the European Butterfly Indicator for Grassland species. Both butterfly indicators show a decline during 2012 and the grassland indicator suggests a recovery during 2013.