Semantic Web Applications and Tools for Life Sciences (SWAT4LS) 2015 was held in Clare College, Cambridge University, UK on 8 and 9 December 2015. It was the eight in the SWAT4Ls series and was the largest so far, measured both by attendance and submissions of papers and posters. SWAT4LS moved to a two-day, conference format for the first time. There were 52 papers and software demonstrations submitted to SWAT4LS 2015. There were 28 accepted for presentation at the conference itself, giving an acceptance rate of 54%. This year there were 33 posters. The conference itself had 121 attenders; the tutorial day had 70 attenders and the Hackathon day had 63; these are the largest numbers attending a SWAT4LS conference. Figure 1 shows a map whence SWAT4LS attenders came; SWAT4LS is truly international.